Reluctance type rotating machine with permanent magnets

ABSTRACT

A reluctance type rotating machine includes a stator  1  having armature windings  2  arranged on an inner periphery of the stator  1 , a rotor  3  having a magnetic unevenness in the circumferential direction and a plurality of permanent magnets  6  arranged for negating the armature windings&#39; flux passing between adjoining poles. Each magnet  6  is magnetized in a direction different from a direction to facilitate the rotor&#39;s magnetization. A magnetic portion  7  is provided between the pole and the interpole of the rotor  3 . Owing to the provision of the magnetic portion  7 , when the armature windings are not excited, more than 30% of the permanent magnets&#39; flux is distributed in the rotor  3 . Similarly, when the machine is loaded, the permanent magnets&#39; interlinkage flux is more than 10% of composite interlinkage flux composed of armature current and the permanent magnets.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reluctance type rotating machineequipped with permanent magnets, which is compact with a high output andwhich is capable of rotating in a wide range by its adoption of a newpole structure.

2. Description of the Related Art

As shown in FIG. 1, an earlier reluctance type rotating machinecomprises a stator 1 having armature windings 2 and a salient-pole rotor3 having an uneven core 4 since the rotating machine does not requirecoils for forming a field system about the rotor 3. Therefore, thereluctance type rotating machine is simple in structure and low inprice.

We now describe a principle of producing the output of the reluctancetype rotating machine. Because of unevenness about the rotor, thereluctance type rotating machine exhibits small magnetic reluctance atprotrusions of the rotor and large magnetic reluctance at recesses ofthe rotor. That is, there is a difference of stored magnetic energybetween a gap over the protrusion and another gap over the recess. Theoutput of the reluctance type rotating machine comes from the change inmagnetic energy. Note, the protrusions and recesses may be provided by aconfiguration allowing the unevenness to be formed not onlygeometrically but magnetically, in other words, the configuration wherethe magnetic reluctance and distribution of magnetic flux density varydepending on the position of the rotor.

As another high-performance rotating machine, there is a permanentmagnet type rotating machine. In the rotating machine, a plurality ofpermanent magnets are arranged on the substantial whole periphery of therotor core although the armature windings of the machine is similar tothe armature windings of an induction machine, the same windings of thereluctance type rotating machine, etc.

Due to the unevenness about the core surface, the reluctance typerotating machine has different magnetic reluctance which depends on therotational position of the rotor. This change in magnetic reluctancecauses the magnetic energy to be varied thereby to produce an output ofthe rotor.

In the conventional reluctance type rotating machine, however, theincreasing of currents causes a local magnetic saturation to be enlargedat the protrusions of the rotor 4. Thus, the enlarged magneticsaturation also causes magnetic flux leaking to the recesses betweenpoles to be increased, so that effective fluxes are decreased whilelowering the output power.

On the other hand, as another high-powered rotating machine, there is apermanent magnet type rotating machine using “rare-earth metal ”permanent magnets having high magnetic energy products. Owing to thearrangement of the permanent magnets on the surface of the rotor core,when the permanent magnets of high energy are employed to form amagnetic field, the permanent magnet type rotating machine is capable offorming an intense magnetic field in an air-gap of the machine,providing a compact and high-powered rotating machine.

Nevertheless, it should be noted that a voltage induced in the armaturewindings gets larger in proportional to the rotating speed of the rotorsince the magnetic flux of each magnet is constant. Therefore, if themachine is required to operate at a wide range of variable speeds up tothe high-speed rotation, it is difficult to carry out the “rated-output” operation of the machine at a rotating speed twice or more as large asthe base speed under constant current and voltage.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide areluctance type rotating machine which is compact in spite of highoutput and which is capable of operating at a wide range of variablespeeds.

To achieve the object of the present invention described above, from the1st aspect of the invention, there is provided a reluctance typerotating machine comprising:

a stator having armature windings;

a rotor having a rotor core, the rotor being provided, in acircumferential direction thereof, with a magnetic unevenness;

a plurality of permanent magnets arranged in the rotor core, fornegating the armature windings' flux passing between adjoining polesdefined in the rotor, each of the permanent magnets being magnetized ina direction different from a direction to facilitate the rotor'smagnetization; and

wherein a magnetic portion is ensured in the rotor core so that, whenthe armature windings are not excited, more than 30% (percent) of thepermanent magnets' flux is distributed in the rotor and also that, whenthe machine is loaded, the permanent magnets' interlinkage flux is morethan 10% of composite interlinkage flux composed of current and thepermanent magnets.

It is noted that the above composite interlinkage flux is changed by aphase difference between the flux vector of current and the flux vectorof permanent magnets. Therefore, we now define the amount of compositeinterlinkage flux when both phases exerting no influence on each otherare on the crossing condition at a right angles, as the above compositeinterlinkage flux of the invention.

As the magnetic unevenness is formed about the rotor core, a magneticprotrusion of the unevenness constitutes a pole of a reluctance motor,while a magnetic recess does an interpole (i.e. a part between theadjoining poles) of the motor. Namely, the magnetic protrusioncorresponds to a “easy-magnetizing” direction to facilitate the rotor'smagnetization, while the magnetic recess corresponds to a“hard-magnetizing” direction where it is difficult to magnetize therotor.

According to the invention, the permanent magnets are arranged in themagnetic recesses in the rotor core. Additionally, in the rotor core,there is provided a magnetic portion for closing the permanent magnets'flux in a short circuit so that, when the armature windings are notexcited, more than 30% (percent) of the permanent magnets' flux isdistributed in the rotor. With this structure, it is possible to reducean induced voltage generating at the rotor's rotating to 0 to 70% of therated voltage for the rotating machine. For example, under conditionthat the induced voltage is set to 33%, even if rotating the rotatingmachine at high speed of three times as fast as the base speed, therewould be no possibility to apply an excessive current to an electriccircuit.

Next, when the machine is loaded, the above magnetic portion isintensely subjected to the magnetic saturation by the flux due to theload current. Consequently, the permanent magnets' flux distributingbetween the poles does increase. According to the invention, themagnetic portion between the poles constitutes a magnetic path so that apart of permanent magnets' flux is distributed in the direction of thecenter-axis of interpole. Additionally, the magnetic portion is adaptedin a manner that, when the machine is loaded, the permanent magnets'interlinkage flux is more than 10% of composite interlinkage fluxcomposed of armature current and the permanent magnets.

The flux of each permanent magnet has an action to repulse the armaturecurrent flux entering along the center-axis direction of the interpoleand increase the magnetic reluctance in the direction of the magnetsince the relative permeability of the magnet is generally equal tozero. Thus, since the permanent magnets' flux and the armature flux inthe opposite direction cancel each other, the composite flux along thecenter-axis direction of the interpole gets fewer or flows in adirection opposite to the armature current when the armature current issmall.

Therefore, since the interlinkage flux along the center-axis directionof the interpole gets smaller, a change within the magnetic unevennessabout the rotor is so enhanced that the output of the machine doesincrease. On the other hand, the armature flux has a tendency ofdistribution to pass through the magnetic protrusions of the rotor corein concentration. Consequently, as the unevenness of flux density aboutthe air-gap is promoted, the magnetic-energy change becomes larger toprovide the machine with high torque and high power factor.

As to an adjusting range of terminal voltage required for operating themachine at a wide range of variable speeds, the function will bedescribed below.

According to the invention, since the permanent magnets are embedded inthe interpoles locally, the surface area of the permanent magnet on theperipheral side of the rotor is smaller than that of the conventionalrotating machine where the permanent magnets are arranged about thewhole periphery of the rotor surface, so that the interlinkage flux bythe magnets gets fewer, too. Then, the interlinkage flux due to thearmature current (both exciting current component and torque currentcomponent of the rotating machine) takes part in the interlinkage fluxof the permanent magnets, so that a terminal voltage is induced.

In the permanent magnet type rotating machine, it is possible to adjustthe terminal voltage because the interlinkage flux of the permanentmagnets occupies almost the whole terminal voltage. On the contrary,since the rotating machine of the invention has a small interlinkageflux of the permanent magnets, it is expected that when adjusting theexciting current widely, then it is possible to control terminal voltagein a wide range. That is, since the exciting current component can beadjusted so that the voltage is less than a power source voltagecorresponding to the velocity, the rotating machine is capable ofoperating at a wide range of variable-speeds under the power source ofconstant voltage. Additionally, since a part of each permanent magnetflux leaks through the above-mentioned magnetic portion forming theshort circuit, it is possible to reduce diamagnetic field inside thepermanent magnet. Thus, since an operating point on a demagnetizingcurve expressing the B(magnetic flux)−H(field intensity) characteristicsof the permanent magnet is elevated (causing a large permeancecoefficient), the demagnetizing-proof characteristics with respect toboth temperature and armature reaction is improved. Particularly, incase of canceling the permanent magnets' flux by the armature currentforming the flux in the directions of the interpole-axes, it is possibleto prevent the demagnetization of the rotor although the demagnetizingfield is applied on the magnets.

Furthermore, since the permanent magnets are embedded in the rotor core,it acts as a retaining mechanism of the permanent magnets, so that therotating machine can ensure its high-speed operation.

According to the 2nd aspect of the invention, there is provided areluctance type rotating machine comprising:

a stator having armature windings;

a rotor having a rotor core, the rotor being provided, in acircumferential direction thereof, with a magnetic unevenness;

a plurality of permanent magnets arranged in the rotor core, fornegating armature flux passing between adjoining poles defined in therotor, each of the permanent magnets being magnetized in a directiondifferent from a direction to facilitate the rotor's magnetization; and

wherein a magnetic portion is ensured in the rotor core so that, whenthe armature windings are not excited, more than 80% (percent) of thepermanent magnets' flux is distributed in the rotor and also that, whenthe machine is loaded, the permanent magnets' interlinkage flux is morethan 5% of composite interlinkage flux composed of current and thepermanent magnets.

Although the basic function of this rotating machine is similar to thatthe previously-mentioned rotating machine, the induced voltage isremarkably small because more than 80% of the permanent magnets' flux isdistributed in the rotor when the armature windings are not excited.Consequently, even if the short circuit is caused in the power source orso, a current originating in the voltage induced by the permanentmagnets is so insignificant to prevent the machine from being burned orbraked excessively. Further, since the stator core loss caused by themagnets' flux gets fewer, the machine's efficiency can be improved whenit is under unloaded or slight-loaded condition.

In addition, the magnetic portion is adapted in a manner that, when themachine is loaded, the permanent magnets' interlinkage flux is more than5% of composite interlinkage flux composed of armature current and thepermanent magnets. Since the magnets' flux and the armature flux canceleach other under the loaded condition, the composite flux in thedirections of center axes of the interpoles is reduced.

Consequently, because of reduced interlinkage flux in the direction ofcenter axes, the magnetic unevenness about the rotor is enhanced toincrease the output of the machine. Simultaneously, since theinterlinkage flux in the direction of center axes of the interpoles isdecreased, the terminal voltage is lowered, whereby the power factor ofthe machine can be improved. Again, the current flux is distributed soas to pass through the poles in concentration.

From the above, as the change in flux density of the gap is increased inthe present invention, the change in magnetic energy is also increasedthereby producing high torque and high power factor.

Furthermore, this rotating machine can perform the following action.Since almost all the flux of each permanent magnet leaks through themagnetic portion of the short circuit, it is possible to reducediamagnetic field inside the permanent magnet remarkably. Thus, since anoperating point on the demagnetizing curve expressing the B(magneticflux)−H(field intensity) characteristics of the permanent magnet is alsoelevated (causing a large permeance coefficient), it is possible to usethe permanent magnets having a deteriorated temperature characteristic,at a temperature of 50 to 200° C. Even if flowing a large current of twoor three times as large as a rated current in an atmosphere ofhigh-temperature, there is no possibility that the permanent magnets aredemagnetized owing to the armature reaction. Especially under acondition of the rated torque current, if increasing the armaturecurrent in order to accomplish a maximum torque of several times as muchas the normal torque in case of negating the permanent magnets' flux bythe armature current forming the flux in the directions of interpoles,there is produced a gap flux in the opposite direction to theinterlinkage flux of the permanent magnets by the armature current. Insuch a case, the rotating machine of the embodiment allows the permanentmagnets to be used without being demagnetized.

Also in this rotating machine, since the permanent magnets are embeddedin the rotor core, it acts as the retaining mechanism of the permanentmagnets, so that the rotating machine can ensure its high-speedoperation.

According to the 3rd aspect of the invention, there is provided areluctance type rotating machine comprising:

a stator having armature windings;

a rotor having a rotor core, the rotor being provided, in acircumferential direction thereof, with a magnetic unevenness;

a plurality of permanent magnets arranged in the rotor core, fornegating the armature windings' flux passing between adjoining polesdefined in the rotor, each of the permanent magnets being magnetized ina direction different from a direction to facilitate the rotor'smagnetization; and

wherein, in a magnetic flux of the permanent magnets at an air gap, anamplitude in a fundamental component of a magnetic flux density of thepermanent magnets is 0.2 to 0.6 T.

According to the 4th aspect of the invention, in common with theabove-mentioned rotating machines, the magnetizing direction of thepermanent magnets is substantially identical to the circumferentialdirection of the rotor. In this case, since the flux of exciting currentcomponent passing the poles intersects the magnetizing direction of thepermanent magnets in substantial right angles in electrical angle, themagnetic saturation due to the current is eased at the respective poles,so that the reluctance torque grows larger.

According to the 5th aspect of the invention, the rotor is provided,between the adjoining poles, with a first non-magnetic part. Owing tothe provision of the first non-magnetic part at each interpole, themagnetic reluctance in the direction of the interpoles is remarkablyincreased. Therefore, since a large unevenness is produced in fluxdensity at the gap, it is possible to produce a large output of themachine because of the increased change in magnetic energy.

According to the 6th aspect of the invention, a width of each pole is0.3 to 0.5 times as long as a pole pitch which corresponds to acircumferential distance from a center of an pole to a center of theadjoining pole.

With this establishment of the pole and interpole, it is possible toeffectively increase the change in the gap flux density with respect tothe position of the rotor, where the rotating machine of high output canbe provided.

According to the 7th aspect of the invention, the rotor has magneticportions each formed on the periphery between the adjoining poles, formagnetically connecting therebetween. Owing to the provision of themagnetic portions, the magnetic material uniformly spreads over thewhole periphery of the rotor with respect to core teeth of the stator.Consequently, the change of magnetic reluctance caused by slots of thestator gets smaller while decreasing the slot ripple. Further, thesmooth surface of the rotor allows the windage loss to be reduced. It isalso possible to restrict the demagnetizing field, which is caused bythe armature current acting on the permanent magnets, owing to themagnetic portions outside the interpoles.

According to the 8th aspect of the invention, the rotor is provided witha second non-magnetic part for reducing flux leaking through respectiveinward portions of the permanent magnets in the radial direction. Owingto the provision of the non-magnetic part on the inner end of eachpermanent magnet, it is possible to prevent the flux from leaking out ofthe magnet. Therefore, it is possible to reduce a volume of thepermanent magnet without remarkably deteriorating the characteristic ofthe machine.

According to the 9th aspect of the invention, the first non-magneticpart between the adjoining poles is positioned so as not to increasemagnetic reluctance outside the permanent magnets remarkably.

Since the first non-magnetic part does not increase the magneticreluctance outside the magnet, it is possible to ensure sufficient fluxin spite of small quantity of permanent magnets.

Further, by the first non-magnetic part, the permanent magnets' flux isdistributed in the rotor's surface opposing the stator when the armaturewindings are not excited. When the flux due to the load currentoverlaps, each magnetic portion between the pole and the interpole andthe outer magnetic portion are subjected to the magnetic saturation, sothat the permanent magnets' flux closing in the rotor interlinks withthe stator. Therefore, when the machine is not loaded, the inducedvoltage due to the interlinkage flux of the permanent magnets is sosmall, whereby the flux of the permanent magnets can be utilizedeffectively under the loaded condition.

According to the 10th aspect of the invention, a gap length outside theinterpole of the rotor is larger than the gap length outside the pole.

Since the gap length outside the pole is smaller than the gap lengthoutside the interpole, the magnetic unevenness is further enlarged, sothat the reluctance torque does increase. When the armature windings arenot excited, the permanent magnets' flux interlinking with the armaturewindings is decreased thereby to close in the rotor core through themagnetic portion between the adjoining poles because the gap lengthoutside the interpole is relatively long.

When the flux of current overlaps at the time of the machine beingloaded, the rotor is locally subjected to the magnetic saturation, sothat the permanent magnets' flux closing in the rotor is brought intothe interlinkage with the stator. Therefore, when the machine is notloaded, the induced voltage due to the interlinkage flux of thepermanent magnets is so small, whereby the permanent magnets' flux canbe effectively increased under the machine's loaded condition.

According to the 11th aspect of the invention, the reluctance typerotating machine is characterized in that the flux due to an armaturecurrent in a center axis-direction between the adjoining poles and theflux of the permanent magnets negates each other, so that the compositeflux in the center axis-direction is substantially equal to zero.

When applying the load current, the flux of the armature current negatesthe permanent magnets' flux, so that the composite flux in the centeraxis of the interpole amounts to zero. Therefore, the voltage induced bythe flux in the central axis of the interpole becomes to be zero, too.Thus, since the terminal voltage is induced by the flux in the directionof pole, low voltage and high output can be provided for the rotatingmachine.

Additionally, the constant output characteristic can be obtained withease. As the reluctance torque is a product of both exciting current andtorque current component of the armature, the output is obtained by aproduct of the exciting current, the torque current component and therotating speed Upon fixing the armature current component (torquecurrent) forming the flux in the direction of interpole axis into aconstant value so that the composite flux in the direction of centeraxis of the interpose amounts to zero, by adjusting the armature currentcomponent (exciting current) with respect to the rotating speed ininverse proportion to each other, the constant output characteristicwhere torque times rotating speed is constant can be accomplished.

According to the 12th aspect of the invention, under condition that anarmature current component forming the flux in the centralaxis-direction between the adjoining poles becomes a maximum, the fluxdue to the armature current component in the center axis-directionbetween the adjoining poles and the flux of the permanent magnetsnegates each other, so that the composite flux in the centeraxis-direction is substantially equal to zero.

In this case, the maximum current for the rotating machine is dividedinto two vector components crossing at right angles, i.e., an armaturecurrent component forming the flux in the direction of center axis ofthe interpole and another armature current forming the flux in thedirection of pole. When the maximum current of armature (compositevector) intersects the armature current component forming the flux inthe direction of center axis of interpole at angles of 45 degrees, amaximum of reluctance torque can be obtained. The rotating machine ofthe invention is constructed in a manner that, at this current phase,the flux of armature current in the direction of the central axis of theinterpole negates the flux of each permanent magnet and therefore, theresultant composite flux in the interpole direction amounts tosubstantial zero. Therefore, when the induced voltage is raised duringthe machine's operation at a high rotating speed range, the machineallows the armature current component (i.e. exciting current component)forming the flux in the direction of pole to be adjusted smaller,whereby the constant induced voltage can be attained. Consequently, itis possible to operate the machine at a wide range of variable-speedsand realize the high power factor while maintaining the constant output.

According to the 13th aspect of the invention, in connection with thearmature current produced by the flux of the permanent magnets when themachine is electrically closed in a short circuit, the interlinkage ofmagnetic flux produced by the permanent magnets in case of the armaturecurrent of zero interlinking with the flux of the permanent magnets isdetermined in a manner that heat derived from Joule-loss originating inthe armature current is less than a thermal allowable value of themachine or braking force produced by the armature current is less thanan allowable value in the rotating machine.

If the permanent magnets' flux which interlinks with the armaturewindings exists when an electrical short-circuit accident is caused inan inverter, a terminal or the like, the rotation of the rotor causes aninduced voltage to be generated. Due to this induced voltage, theshort-circuit current may flow in the armature windings for burning oran operation of the apparatus may be locked by excessive brake torque.According to the invention of the 1st and 2nd aspects, since the highoutput of the machine is accomplished by the interlinkage flux fromsmall number of permanent magnets, it is possible to reduce the inducedvoltage in order to establish both short-circuit current and brake lessthan the allowable values, respectively. Consequently, even if occurringthe short-circuit accident, it would be possible to prevent troubles inthe rotating machine and the apparatus.

According to the 14th aspect of the invention, the permanent magnets arearranged between the adjoining poles and the first non-magnetic partbetween the poles is provided with a conductive material.

With the arrangement of the conductive material in the firstnon-magnetic magnetic part, an eddy current is generated in theconductive materials when the rotor does not synchronize with therotating field, so that the rotor can enter its synchronous rotation.That is, the self-starting and stable rotation of the rotating machinecan be realized.

According to the 15th aspect of the invention, the rotor is provided, ona periphery thereof, with a plurality of conductive members extending inthe axial direction of the rotor.

Since the induced current flows in the conductive members at themachine's asynchronous operation, the self-starting and stable rotationof the rotating machine can be realized. Further, it is possible toabsorb the eddy current by harmonic current when driving the inverter.

According to the 16th aspect of the invention, the reluctance typerotating machine further comprises a pair of magnetic end rings arrangedon respective axial ends of the rotor.

When the rotor is subjected to an armature reaction field in theopposite direction to the magnetized direction of each permanent magnetin the rotor core by the armature current, a part of magnetic flux ofthe permanent magnets forms closed magnetic paths each flowing the corein the axial direction, entering into the end ring and returning thecore. That is, since the leakage flux can be produced effectively, it ispossible to adjust the amount of interlinkage flux between the armaturewindings and the permanent magnets, whereby the terminal voltage can becontrolled by the armature current with ease. In addition, it ispossible to adjust the ratio of leakage flux to effective flux bycontrolling a clearance between the rotor core and each end ring.

According to the 17th aspect of the invention, the object of the presentinvention can be also accomplished by a reluctance type rotating machinecomprising:

a stator having armature windings;

a rotor having a rotor core, the rotor being provided, in acircumferential direction thereof, with a magnetic unevenness;

a plurality of permanent magnets arranged in the rotor core alongdirections of respective poles of the rotor, for negating armature fluxpassing between adjoining poles defined in the rotor; and

wherein each interpole between the adjoining poles has an outer facerecessed with respect to an outer face of the pole in the radialdirection of the rotor.

According to the above invention, since the outer face of each“interpole” (or an inter-pole portion) of the rotor is recessed withrespect to the outer face of the “pole” (or a magnetic pole portion) inthe radial direction of the rotor, a gap length in the radial directionof the rotor between the stator and the rotor changes, so that themagnetic unevenness is formed about the rotor. While, since thepermanent magnets are magnetized so as to negate the armature fluxpassing the “interpoles” (i.e. interpole portions), each magneticreluctance in the direction along each interpole is increased. Thus, anunevenness is produced in the magnetic flux density at the gap betweenthe stator and the rotor, whereby a great torque can be produced in therotating machine by the resultant change in magnetic energy.

According to the 18th aspect of the invention, in the rotating machineof the 17th aspect, each of the permanent magnets is arranged so as toleave a part of the rotor core between an outer end of the permanentmagnet in the radial direction of the rotor and an outer periphery ofthe rotor.

According to the 19th aspect of the invention, in the rotating machineof the 18th aspect, the part between the outer end of the permanentmagnet and the outer periphery of the rotor has a radial thickness to bemagnetically saturated by the armature flux.

According to the 20th aspect of the invention, in the rotating machineof the 18th aspect, it is preferable that the part between the outer endof the permanent magnet and the outer periphery of the rotor has aradial thickness smaller than a radial thickness of the interpole at acenter thereof.

According to the 21st aspect of the invention, in the rotating machineof the 18th aspect, it is preferable that the part between the outer endof the permanent magnet and the outer periphery of the rotor has aradial thickness so that, when no current flows in the armaturewindings, the magnetic flux density of the permanent magnetsinterlinking with the armature windings gets less than 0.1 T at the gapbetween the rotor and the stator.

In common with the 18th to 21st aspects of the invention preferablearrangements, owing to the provision of a part of core between eachpermanent magnet and the outer periphery of the rotor, the flux from themagnet is closed in the rotor core when the armature current is zero, inother words, the machine is unloaded. Thus, since the induced voltage inthe armature windings is substantially equal to zero, the rotatingmachine allows the rotor to rotate at a constant speed without beingbraked from the stator's side. Further, even if an electricalshort-circuit occurs the armature windings, an inverter, etc. during therotor's rotation, the short-circuit current does not flow since theinduced voltage is substantially equal to zero. Therefore, in spite ofthe short-circuit, it is possible to prevent an excessive braking forcefrom being produced and the armature windings from being damaged. Whenthe machine is loaded, the armature flux in the directions of the polespartially passes through the outer core portion outside the permanentmagnets, so that each interpole is magnetically saturated at both endsof the interpole in the circumferential direction. Consequently, theflux of the permanent magnets is distributed out of the rotor andinterlinks with the armature windings, whereby the output and powerfactor of the machine can be improved.

According to the 22nd aspect of the invention, in the machine of any oneof the 18th to 21st aspects, each of the permanent magnets is arrangedso as to form a space between the outer end of the permanent magnet andthe outer periphery of the rotor, in addition to the part of the rotorcore.

According to the 23rd aspect of the invention, the space is filled upwith a non-magnetic material.

According to the 24th aspect of the invention, a cavity is formed ineach interpole portion of the rotor core.

In the above cases, since the cavity or the non-magnetic material actsas the magnetic reluctance, it is possible to reduce the leakage fluxflowing from the pole to the interpole effectively.

According to the 25th aspect of the invention, the object of the presentinvention described above can be also accomplished by a reluctance typerotating machine comprising:

a stator having armature windings;

a rotor having a rotor core, the rotor being provided, in acircumferential direction thereof, with a magnetic unevenness and alsodefining magnetic poles and interpoles in the rotor core by turns;

a plurality of permanent magnets arranged in the rotor core alongdirections of respective poles of the rotor, for negating armature fluxpassing between adjoining poles defined in the rotor; and

a conductor arranged on a peripheral portion of the rotor core, forgenerating an induced current in the conductor.

With the above-mentioned arrangement of the conductor, an inducedelectromotive force is produced in the conductor owing to theelectromagnetic induction at the machine's starting, therebyaccomplishing the self-starting of the rotating machine.

While, since the permanent magnets are magnetized so as to negate thearmature flux passing the interpoles, each magnetic reluctance in thedirection along each interpole is increased to produce an unevenness inthe magnetic flux density at the gap between the stator and the rotor.Thus, a great torque can be produced in the rotating machine by theresultant change in magnetic energy.

According to the 26th aspect of the invention, in the machine of the25th aspect, the conductor is constituted by a plurality of magneticbars which are embedded in the vicinity of an outer face of each pole ofthe rotor core so as to extend in the axial direction of the rotor.

In this case, owing to the provision of the magnetic bars as theconductor, the machine is capable of self-starting by theirconductivity. Additionally, as the bars are made of magnetic material,the density of flux (main flux) flowing the poles is not reduced, sothat there is no possibility to exert an influence on the machinetorque.

According to the 27th aspect of the invention, in the machine of the26th aspect, the rotor has cavities formed in respective core portionsoutside the permanent magnets in the radial direction of the rotor.

In this case, the magnetic circuit is interrupted by each of thecavities, so that the magnetic reluctance of the interpoles is furtherincreased. Therefore, the change in magnetic energy between each poleand each interpole is so increased thereby to generate a great torque.

According to the 28th aspect of the invention, in the machine of the27th aspect, the rotor core is provided, in the vicinity of an outerface of each interpole, with a plurality of non-magnetic conductor barsextending in the axial direction of the rotor and generating an inducedcurrent therein.

In this case, owing to the addition of the non-magnetic conductor bars,the self-starting characteristic of the machine is further progressed.Further, the non-magnetism of the bars allows the magnetic reluctance ofthe interpoles to be increased furthermore, so that the change inmagnetic energy is further increased.

According to the 29th aspect of the invention, in the machine of the28th, aspect, the cavities of the rotor are filled up with part aplurality of non-magnetic conductor bars extending in the axialdirection of the rotor and generating an induced current therein.

In this case, since the magnetic circuit is interrupted by thenon-magnetic conductor bar in each cavity, the magnetic reluctance ofthe interpoles is further increased in comparison with the case of onlyproviding the cavities in the interpoles. Further, the strength of therotor per se is improved by embedding the bars in the cavities.

According to the 30th aspect of the invention, in the machine of the25th aspect, the conductor comprises a plurality of deep groove magneticbars which are embedded in the vicinity of an outer face of each pole ofthe rotor core so as to extend in the axial direction of the rotor and aplurality of non-magnetic bars which are embedded in the vicinity of anouter face of each interpole of the rotor core so as to extend in theaxial direction of the rotor.

In this case, since the conductive bars are embedded along the wholeperiphery of the rotor core, the starting capability similar to a caseof using an exclusive starting cage can be attained by the conductivityof the bars. Further, owing to respective material choices for the polesand interpoles, a difference in magnetic reluctance between each poleand each interpole is increased. Consequently, the change in magneticenergy is further increased.

According to the 31st aspect of the invention, in the machine of the25th aspect, the conductor is constituted by a plurality of non-magneticbars which are embedded in the vicinity of an outer face of eachinterpole of the rotor core so as to extend in the axial direction ofthe rotor.

In this case, the magnetic reluctance in the interpoles is increased bythe non-magnetism of the non-magnetic bars. Further, since the poles isprovided with no bar, the structure of the rotor is simplified.

According to the 32nd aspect of the invention, in the machine of the25th aspect, the conductor is adapted so as to cover an outer face ofthe rotor core.

In this case, since the induced current flows in the outer periphery ofthe rotor smoothly due to the conductivity of the conductor at themachine's starting, the machine is capable of starting by itself. Inaddition, since the rotor is covered with the conductor, the mechanicalstrength of the rotor can be improved.

According to the 33rd aspect of the invention, in the machine of the32nd aspect, the conductor has a cylindrical shape so as to cover thewhole outer face of the rotor core.

Then, in addition to the improved self-starting capability, thecylindrical conductor allows the mechanical strength to be improved withits simple structure.

According to the 34th aspect of the invention, in the machine of the32nd aspect, the conductor is constituted by a plurality of shellmembers connected with the outer faces of the poles to cover theinterpoles.

In this case, since the shell members are connected with the outer facesof the poles, the air resistance (or windage loss) during the rotor'srotation is reduced thereby to enhance a rotational efficiency of therotor.

According to the 35th aspect of the invention, in the machine of the25th aspect, the conductor is arranged in the vicinity of an outer faceof each interpole of the rotor core and curved along the circumferentialdirection of the rotor.

In this case, when the machine is starting, the induced current flows inthe interpoles, allowing the self-starting of the rotor.

According to the 36th aspect of the invention, in the machine of the25th aspect, the conductor has a plurality of slits formed in acylindrical portion of the rotor core and arranged along thecircumferential direction of the rotor.

Due to the formation of the slits, the induced current at the machine'sstarting flows while defining a long path in the axial andcircumferential directions of the rotor. Consequently, the magneticcoupling between the armature windings and the rotor is reinforced toprovide a great starting torque for the rotor.

According to the 37th aspect of the invention, in the machine of the36th aspect, the conductor is formed so as to cover the outer face ofthe rotor core.

In this case, since the induced current flows in the outer periphery ofthe rotor smoothly, it facilitates the self-starting of the machinefurthermore. In addition, since the rotor is covered with the conductor,the mechanical strength of the rotor can be further improved.

According to the 38th aspect of the invention, in the machine of the37th aspect, the conductor has a cylindrical shape so as to cover thewhole outer face of the rotor core.

Then, in addition to the improved self-starting capability, thecylindrical conductor allows the mechanical strength to be improved withits simple structure. Moreover, the air resistance (or windage loss)during the rotor's rotation is reduced thereby to enhance the rotationalefficiency of the rotor.

According to the 39th aspect of the invention, in the machine of the38th aspect, the conductor is constituted by a plurality of shellmembers connected with the outer faces of the poles to cover theinterpoles.

Also in this case, since the shell members are connected with the outerfaces of the poles, it is possible to reduce the air resistance (orwindage loss) during the rotor's rotation, whereby the rotationalefficiency of the rotor can be enhanced.

According to the 40th aspect of the invention, in the machine of the36th aspect, the conductor is arranged in the vicinity of an outer faceof each interpole of the rotor core and curved along the circumferentialdirection of the rotor.

Also in this case, when the machine is starting, the induced currentflows in the interpoles, allowing the self-starting of the rotor.

According to the 41th aspect of the invention, in the machine of the37th or the 38th aspect, the conductor is made of conductive magneticmaterial.

Then, it is possible to make the rotor's magnetic reluctance against themain flux smaller while making the main flux larger. Furthermore, sincethe slipping gets smaller at the machine's pulling-in, the machine iscapable of starting and pulling-in with respect to such a load asrequiring a large torque to drive.

According to the 42nd aspect of the invention, the object of the presentinvention described above can be also accomplished by a reluctance typerotating machine comprising:

a stator having armature windings;

a rotor consisting of a rotor core and an annular member outside therotor core; and wherein

the rotor core includes a plurality of poles each consisting of a coreportion projecting outward in the radial direction of the rotor and aplurality of interpoles each disposed between the adjoining poles in thecircumferential direction of the rotor; and

the annular member is fitted to the rotor core so as to surround theperipheries of the poles.

In this case, since the peripheries of the poles of the rotor core iscovered with the annular member, the interpoles of the rotor isreinforced to allow the bridge portions of the interpoles to be thinned.Therefore, the leakage of the q-axis flux through the bridge portions isreduced to enhance the magnetic reluctance of the interpoles.

According to the 43rd aspect of the invention, in the machine of the42nd aspect, the rotor is provided, on respective side faces of thepoles in the circumferential direction, with a plurality of permanentmagnets which are magnetized so as to negate armature flux passingthrough the interpoles.

In this case, since the permanent magnets' flux opposes the q-axis flux,the magnetic reluctance in the interpoles is enhanced to improve theoutput of the machine.

According to the 44th aspect of the invention, in the machine of the40th. aspect, the annular member is made of magnetic material.

In this case, the d-axis flux is easy to pass through the pole portions,so that the main flux can be increased.

According to the 45th aspect of the invention, in the machine of the42nd. aspect, the annular member is constituted by material of whichsaturation flux density is lower than that of material forming the rotorcore.

In this case, the resultant rotor (rotor core and annular member) has alowered saturation flux density in the bridge portions in comparisonwith the conventional rotor where the adjoining poles are connected witheach other through the rotor core material in the interpole. Thus, themagnetic reluctance can be enhanced in spite of the bridge portions ofthe identical thickness.

According to the 46th aspect of the invention, there is also provided amethod of manufacturing a rotor of a rotating machine, comprising thesteps of:

preparing a rotor core having a plurality of poles each consisting of acore portion projecting outward in the radial direction of the rotor anda plurality of interpoles each disposed between the adjoining poles inthe circumferential direction of the rotor;

arranging a plurality of permanent magnets before magnetization onrespective side faces of the poles in the circumferential direction ofthe rotor,

setting the rotor core on a magnetizing unit thereby to magnetize thepermanent magnets; and thereafter,

fitting an annular member to the rotor core in a manner that the annularmember surrounds the peripheries of the poles.

Since the rotor core to be prepared in the above method is provided withthe pole projecting outward in the radial direction of the rotor and theinterpoles each disposed between the adjoining poles, it is possible toapproach the pre-magnetized magnets, which are attached to the rotorcore, to a magnetizer easily, facilitating the magnetizing operation forthe permanent magnets.

According to the 47th aspect of the invention, there is also provided amethod of manufacturing a rotor of a rotating machine, comprising thesteps of:

preparing a rotor core having a plurality of poles each consisting of acore portion projecting outward in the radial direction of the rotor anda plurality of interpoles each disposed between the adjoining poles inthe circumferential direction of the rotor;

arranging a plurality of permanent magnets after magnetization onrespective side faces of the poles in the circumferential direction ofthe rotor; and thereafter,

fitting an annular member to the rotor core in a manner that the annularmember surrounds the peripheries of the poles.

Also in this case, it is possible to easily insert the magnetizedmagnets into spaces each interposed between the poles from the outsidein the radial direction of the rotor, facilitating the assemblingoperation of the rotor.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims taken in conjunction with the accompany drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an earlier reluctance type rotatingmachine, taken along a radial direction thereof;

FIG. 2 is a cross sectional view of a reluctance type rotating machinein accordance with first, second, ninth, tenth and eleventh embodimentsof the present invention, taken along the radial direction of themachine;

FIG. 3 is a cross sectional view of the reluctance type rotating machinein accordance with the 1st. to 14th. embodiments, showing the flows ofmagnetic flux due to armature currents along the directions of poleaxes;

FIG. 4 is a cross sectional view of the reluctance type rotating machinein accordance with the 1st. to 14th. embodiments, showing the flows ofmagnetic flux due to armature currents along the directions of interpoleaxes;

FIG. 5 is a cross sectional view of the reluctance type rotating machinein accordance with the 1st. to 14th. embodiments, showing the flows ofmagnetic flux due to permanent magnets;

FIG. 6 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 3rd. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 7 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 4th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 8 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 5th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 9 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 6th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 10 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 7th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 11 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 8th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 12 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 13th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 13 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 14th. embodiment of the presentinvention, taken along the axial direction of the machine;

FIG. 14 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 14th. embodiment of the presentinvention, taken along the axial direction of the machine;

FIGS. 15A and 15B are cross sectional views of the reluctance typerotating machine in accordance with the 15th. embodiment and itsmodification of the present invention, taken along the radial directionof the machine;

FIG. 16 is a cross sectional view of the reluctance type rotatingmachine of FIG. 15A, showing the distribution of magnetic flux in arotor when the armature current is equal to zero;

FIG. 17 is a cross sectional view of the reluctance type rotatingmachine of FIG. 15A, showing the distribution of magnetic flux due tothe armature current of d-axis when the machine is loaded;

FIG. 18 is a cross sectional view of the reluctance type rotatingmachine of FIG. 15A, showing the distribution of magnetic flux due tothe armature current of q-axis when the machine is loaded;

FIG. 19 is a cross sectional view of a rotor of a reluctance typerotating machine as a modification of the 15th. embodiment;

FIG. 20 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 16th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 21 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 17th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 22 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 18th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 23 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 19th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 24 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 20th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 25 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 21st. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 26 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 22nd. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 27 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 23rd. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 28 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 24th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 29 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 25th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 30 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 26th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 31 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 27th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 32 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 28th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 33 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 29th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 34 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 30th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 35 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 31st. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 36 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 32nd. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 37 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 33rd. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 38 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 34th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 39 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 35th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 40 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 36th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 41 is a perspective view of a cylindrical conductive memberemployed for the rotor of FIG. 40;

FIG. 42 is a cross sectional view of the reluctance type rotatingmachine in accordance with the 37th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 43 is a perspective view of a cylindrical conductive memberemployed for the rotor of FIG. 42;

FIG. 44 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 38th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 45 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 39th. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 46A is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 40th. embodiment of the presentinvention, taken along the radial direction of the machine and FIG. 46Bis a perspective view of a shell member (conductor) of FIG. 46A;

FIG. 47 is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 41st. embodiment of the presentinvention, taken along the radial direction of the machine;

FIG. 48A is a cross sectional view of a rotor of the reluctance typerotating machine in accordance with the 42nd. embodiment of the presentinvention, taken along the radial direction of the machine and FIG. 48Bis a perspective view of a shell member (conductor) of FIG. 48A;

FIG. 49 is a cross sectional view of a reluctance type rotating machinein accordance with the 43rd. embodiment of the present invention, takenalong the radial direction of the machine;

FIG. 50 is a cross sectional view of the reluctance type rotatingmachine of the 43rd. embodiment, showing the flux distribution due toarmature current of d-axis;

FIG. 51 is a cross sectional view of the reluctance type rotatingmachine of the 43rd. embodiment, showing the flux distribution due toarmature current of q-axis;

FIG. 52 is a cross sectional view of a reluctance type rotating machinein accordance with the 44th. embodiment of the present invention, takenalong the radial direction of the machine;

FIGS. 53A to 53D are schematic views showing a method of manufacturing arotor of the reluctance type rotating machine of the 44th. embodiment ofthe present invention; and

FIG. 54 is a schematic plan view of an earlier rotor.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A great number of embodiments of the present invention will be describedwith reference to the drawings. Note, common elements in some groups ofthe embodiments are indicated with the same reference numerals,respectively.

[1st Embodiment]

FIG. 2 is a cross sectional view of a reluctance type rotating machinein accordance with the first embodiment of the present invention, takenalong the radial direction of a rotor of the machine. In FIG. 2, astator 1 includes armature windings 2 and accommodates a rotor 3therein. The rotor 3 includes a rotor core 4 and permanent magnets 6.The rotor core 4 defines both easy-directions and hard-directions formagnetization. That is, according to the embodiment, the rotor core 4 iscomposed of a plurality of laminated electromagnetic steel plates eachhaving cavities 5 formed for accommodating eight permanent magnetstherein. The eight cavities 8 are arranged in a cross manner, formingfour salient-poles. Thus, each core portion interposed between twoparallel cavities 5 forms a magnetic projection to provide each pole 4 a(magnetic pole portion), while each core portion between two adjacentcavities 5 in the vertical relationship forms a magnetic recess toprovide an interpole 4 b (magnetic interpole portion). Further arrangedin the cavities 5 are permanent magnets 6 each of which is magnetized soas to negate flux of armature current flowing between the adjacent poles4 a (i.e. interpole 4 b). That is, the permanent magnets 6 on both sidesof each pole 4 a are identical to each other in terms of the magnetizingdirection, while the magnetizing directions of the permanent magnets 6on both sides of each interpole 4 b are opposite to each other in thecircumferential direction of the rotor 3. Preferably, the permanentmagnets 6 are magnetized in the substantially-circumferential directionand more preferably, they are magnetized in respective directionssubstantially perpendicular to the pole axes. Recommended for thepermanent magnets 6 is rare-earth permanent magnets of high energyproduct, preferably, Nd—Fe—B permanent magnets.

A magnetic portion 7 is ensured between each pole 4 a and each interpole4 b and also between the end of each permanent magnet 6 and theperiphery of the rotor core 4 in a manner that 30 to 60% of flux thatthe permanent magnets 6 generate at the machine's no-excitation doesdistribute in the rotor 3. Since the permanent magnets 6 are arranged onthe sufficient inside of the rotor core 4 in this embodiment, the fluxof the permanent magnets 6 is magnetically closed in a short-circuitthrough the magnetic portions 7 as magnetic paths. The radial thicknessof each magnetic portion 7 and the thickness and surface area of eachpermanent magnet 6 are determined so that, preferably, 30 to 40% of fluxof the permanent magnets 6 is distributed in the rotor 3 when themachine is not excited. Further, the radial thickness of each magneticportion 7 and the thickness and surface area of each permanent magnet 6are also determined so that, when the machine is loaded, theinterlinkage flux of the windings 2 by the permanent magnets 6 amountsto 10 to 60% of composite interlinkage flux of the currents andpermanent magnets, more preferably, 30 to 50% of the same.

Further, the radial thickness of each magnetic portion 7 and thethickness and surface area of each permanent magnet 6 are alsodetermined so that, in the magnetic flux of the permanent magnets 6 atan air gap, the amplitude in a fundamental component of the magneticflux density of the permanent magnets 6 is 0.2 to 0.6 T, more preferably0.35 to 0.45 T.

According to the embodiment, a circular thickness W of the pole 4 a inthe circumferential direction is established to be 0.3 to 0.5 times aslong as a pole pitch L (a circumferential distance from the center of apole to that of the neighboring pole).

Next, we describe the operation of the rotating machine.

FIG. 3 shows the flux φd by the d-axis armature current along thedirections of pole axes of the rotor core 4. In the shown structure,since the magnetic path is constituted by the core of the poles 4 a, theflux is easy to flow because the magnetic reluctance is remarkablysmall. Note, in FIG. 3, reference numeral 8 designates one ofnon-magnetic portions.

FIG. 4 shows the flux φq by the q-axis armature current along thedirections of radial axes passing the centers of the interpoles 4 b.Although the magnetic flux φq of the interpoles 4 b forms the magneticpaths crossing the permanent magnets 6 in the interposes 4 b, the fluxby the armature current is reduced by the action of high reluctance ofthe permanent magnets 6 since the relative permeability of the permanentmagnet 6 is substantially equal to 1.

Since the permanent magnets 6 are magnetized in the substantialperpendicular direction to the pole axes, the flux from one pole of eachpermanent magnet 6 flows the magnetic portion 7 in the vicinity of theperiphery of the core 4 and the sequent pole 4 a and finally returnsanother pole of the magnet 6, forming a magnetic circuit φma, as shownin FIG. 5. Further, the flux of each magnet 6 partially flows into thestator 1 through a clearance and returns to the magnet 6 via theneighboring permanent magnet 6 and the pole 4 a, thereby defining amagnetic circuit φmb.

As shown in FIG. 4, since the interlinkage flux of the magnets 6 isdistributed in the opposite direction to the magnetic flux φq of theinterpoles 4 b, the interlinkage flux of the magnets 6 repels thearmature flux φq entering from the interpoles 4 b for their mutualnegation. In the gap portion above the interpoles 4 b, the gap fluxdensity produced by the armature current is reduced due to the flux ofthe permanent magnets 6 to change widely in comparison with the gap fluxdensity above the poles. That is, the change of gap flux density isincreased with respect to the position of the rotor 3, so that thechange of magnetic energy grows larger. Further, owing to the provisionof the magnetic portions 7 on the boundary between the poles and theinterpoles, when the machine is loaded, the rotor is subjected to greatmagnetic saturation by load currents. Consequently, the magnetic flux ofthe magnets 6 distributing between the poles does increase. Thus, asthere is produced a great unevenness in the distribution of gap fluxowing to the magnetic reluctance and flux of the permanent magnets, theresultant magnetic energy is remarkably changed thereby to produce alarge output.

Next, we describe the adjusting range of terminal voltage required foroperating the machine at a wide range of variable speeds.

Since each permanent magnet is disposed in the only part of theinterpole portion in the rotating machine of the embodiment, the surfacearea of the permanent magnet on the peripheral side of the rotor issmaller than that of the conventional rotating machine where thepermanent magnets are arranged about the whole periphery of the rotorsurface, so that the interlinkage flux by the magnets is also decreased.

Additionally, when the machine is not excited, considerable flux of thepermanent magnets 6 flows the magnetic portions 7 to be leakage flux inthe rotor core. Therefore, as the induced voltage can be minimizedremarkably under this state, the core loss will be reduced when themachine is not excited. Further, when the windings 2 are closed in ashort circuit, then the excess current will get smaller.

When loaded, the terminal voltage is induced since the interlinkage fluxdue to the armature current (an exciting current component and a torquecurrent component of the reluctance rotating machine) is added to theinterlinkage flux due to the permanent magnets 6.

In the permanent magnet type rotating machine, it is possible to adjustthe terminal voltage because the interlinkage flux of the permanentmagnets 6 occupies almost the whole terminal voltage. On the contrary,since the rotating machine of the invention has a small interlinkageflux of the permanent magnets 6, the wide adjustment of the excitingcurrent component allows the terminal voltage to be adjusted over a widerange. That is, since the exciting current component can be adjusted sothat the voltage is less than a power source voltage corresponding tothe velocity, the rotating machine is capable of a wide range ofvariable-speed operation from the base speed at a constant voltage.

Further, as the rotating machine does not restrict the voltage by itsforcible field-weakening control, there would be no possibility of theoccurrence of over-voltage even if the control is not effected at themachine's rotation at high speed.

Additionally, since the partial flux φma of each permanent magnet 6leaks through the magnetic portion 7 of the short circuit, it ispossible to reduce diamagnetic field inside the permanent magnet 6.Thus, since an operating point on a demagnetizing curve expressing theB(magnetic flux)−H(field intensity) characteristics of the permanentmagnet is elevated (causing a large permeance coefficient), thedemagnetizing-proof characteristics with respect to both temperature andarmature reaction is improved. Simultaneously, since the permanentmagnets 6 are embedded in the rotor core 4, it acts as a retainingmechanism of the permanent magnets 6, so that the rotating machine canensure its high-speed operation.

Since the circular thickness W of the pole 4 a in the circumferentialdirection is established to be 0.3 to 0.5 times as long as the polepitch L (the circumferential distance from the center of a pole to thatof the neighboring pole), it is possible to increase the change ofmagnetic flux density distribution of the gap effectively, therebyaccomplishing the high-output rotating machine.

[2nd Embodiment]

The reluctance type rotating machine of the 2nd. embodiment will bedescribed with reference to FIG. 2.

In this embodiment, parts similar to those of the 1st. embodiment willbe eliminated in the description.

According to the embodiment, the magnetic portion 7 is ensured betweeneach pole 4 a and each interpole 4 b and also between the end of eachpermanent magnet 6 and the periphery of the rotor core 4 so that 80% ormore of flux that the permanent magnets 6 generate at the machine's noexcitation does distribute in the rotor 3. Additionally, the radialthickness of each magnetic portion 7 and the thickness and surface areaof each permanent magnet 6 are respectively formed thicker than those ofthe 1st. embodiment. In other words, they are determined so that,preferably, 90 to 95% of flux of the permanent magnets 6 is distributedin the rotor 3 at the machine's exciting.

Moreover, the radial thickness of each magnetic portion 7 and thethickness and surface area of each permanent magnet 6 are alsodetermined so that, when the machine is loaded, the interlinkage flux ofthe windings 2 by the permanent magnets 6 amounts to 5% or more ofcomposite interlinkage flux of the currents and permanent magnets, morepreferably, 10 to 30% of the same.

Although the 2nd embodiment is similar to the 1st. embodiment in termsof the machine's basic operation, the induced voltage is remarkablysmall since 80% or more flux generated by the magnets 6 is distributedin the rotor 3. Consequently, even if the short circuit is caused in thepower source or so, a current originating in the voltage induced by thepermanent magnets 6 is so insignificant to prevent the machine frombeing burned or braked excessively.

Furthermore, the rotating machine of the 2nd. embodiment operates asfollows. Since almost all the flux of each permanent magnet 6 leaksthrough the magnetic portion 7 of the short circuit, it is possible toreduce diamagnetic field inside the permanent magnet 6 remarkably. Thus,since an operating point on the demagnetizing curve expressing theB(magnetic flux)−H(field intensity) characteristics of the permanentmagnet is also elevated (causing a large permeance coefficient), it ispossible to use the permanent magnets having a deteriorated temperaturecharacteristic, at a temperature of 50 to 200° C. For example, even ifflowing a large current of two or three times as large as a ratedcurrent in an atmosphere of high-temperature, it is possible to use theMd—Fe—B magnet, which has a high magnetic energy product (40 MGOe) inspite of the deteriorated temperature characteristic, without beingdemagnetized owing to its armature reaction.

[3rd Embodiment]

FIG. 6 is a radial sectional view of a rotor of the reluctance typerotating machine of the 3rd. embodiment of the present invention.

According to this embodiment, the rotor core 4 is provided with ageometric unevenness. As the other constituents are similar to those ofthe 1st. and 2nd. embodiments, their overlapping descriptions will beeliminated.

Owing to the provision of the geometric unevenness, the change of fluxdistribution about the gap is further enlarged and therefore, thereluctance torque is further increased.

[4th Embodiment]

FIG. 7 is a radial sectional view of a rotor of the reluctance typerotating machine of the 4th. embodiment of the present invention.

According to this embodiment, the rotor core 4 is provided, at a centerof each interpole 4 b, with a cavity 8 having a fan-shaped section as afirst non-magnetic part. Provided on the periphery of each cavity 8 is amagnetic portion 9 which operates to connect the pole 4 a with theneighboring pole 4 a magnetically. As the other constituents are similarto those of the 1st. embodiment, their overlapping descriptions will beeliminated.

Since the non-magnetic portion is defined between the adjoining poles 4b by the fan-shaped cavity 8, the magnetic reluctance in the interpoledirection is remarkably increased. Consequently, the reluctance torqueis remarkably increased. Furthermore, the interlinkage flux of themagnets 6 from the interpoles 4 b is restricted by the fan-shapedcavities 8. Therefore, the torque due to the permanent magnets andcurrent decreases, while the reluctance torque increases. That is,without lowering both torque and output, it is possible to reduce theinduced voltage due to the permanent magnets 6.

Additionally, owing to the provision of the magnetic portions 9 each ofwhich connects the adjoining poles 4 a with each other, the rotor core 4uniformly spreads over the whole periphery of the rotor 3 with respectto core teeth of the stator 1. Consequently, the change of magneticreluctance caused by slots of the stator 1 gets smaller while decreasingthe slot ripple. Further, the smooth surface of the rotor 3 allows thewindage loss to be reduced. It is also possible to restrict thedemagnetizing field, which is caused by the armature current acting onthe permanent magnets 6, owing to the magnetic portions 9 outside theinterpoles 4 b.

[5th Embodiment]

FIG. 8 is a radial sectional view of a rotor of the reluctance typerotating machine of the 5th. embodiment of the present invention.

In the rotating machine of this embodiment, a shortened permanent magnet6 and an aluminum material 12 as a second non-magnetic part are providedin each cavity 5 of the rotor core 4. As the other constituents aresimilar to those of the 1st. and 4th. embodiment, their overlappingdescriptions will be eliminated. As the other constituents are similarto those of the 1st. embodiment, their overlapping descriptions will beeliminated.

Owing to the provision of the non-magnetic aluminum material 12 on theinner end of each permanent magnet 6, it is possible to prevent the fluxfrom leaking into the interpole direction, whereby the reduction ofreluctance torque can be restricted. Further, it is possible to decreasethe leakage of flux from the permanent magnet 6 on the inner side of thecore 4. Therefore, it is possible to reduce a volume of each permanentmagnet 6 without remarkably deteriorating the output characteristic ofthe machine.

[6th Embodiment]

FIG. 9 is a radial sectional view of a rotor of the reluctance typerotating machine of the 6th. embodiment of the present invention.

According to the embodiment, the rotor core 4 is provided, on aperiphery thereof, with a geometric unevenness. As other constituentsare similar to those of the 1st. and 5th. embodiments, overlappingdescriptions are eliminated.

Owing to the provision of the geometric unevenness, the change of fluxdistribution about the gap is further increased, so that the reluctancetorque is further increased. As to the other operation and effect, thisembodiment is similar to the 1st. and 5th. embodiments.

[7th Embodiment]

FIG. 10 is a radial sectional view of a rotor of the reluctance typerotating machine of the 7th. embodiment of the present invention.

According to the embodiment, in each interpole 4 b of the core 4, twopermanent magnets 6 are arranged in the vicinity of the periphery of therotor core and magnetized in the circumferential direction of the rotor3. These permanent magnets 6 are characterized by their magnetizingdirections opposing with each other and arranged so as to form amagnetic circuit by a magnetic portion 10 at the center of the interpoleaxis and the magnetic portion 9 as the magnetic paths. Further, thefan-shaped cavity 8 is formed on the inner peripheral side of thepermanent magnets 6 and the magnetic portion 10 interposed therebetween.As other constituents are similar to those of the 1st. embodiment, theiroverlapping descriptions are eliminated.

Owing to the provision of the fan-shaped cavities 8 as the firstnon-magnetic parts, it is possible to provide a rotor where the flux ofthe permanent magnets 6 is distributed the outer magnetic portions 9 ofthe rotor and the stator 1 without a large increase of magneticreluctance outside the magnets 6. That is, since the fan-shaped cavities8 do not increase the magnetic reluctance outside the permanent magnets6, it is possible to ensure the sufficient flux in spite of smallquantity of permanent magnets.

Further, the flux of each permanent magnet 8 is interrupted by eachcavity 8 as the first non-magnetic part and closed in a short circuitthrough the outer magnetic portion 9 as the magnetic path. When the fluxdue to the load current overlaps, each magnetic portion 7 between thepole 4 a and the interpole 4 b and the outer magnetic portion 9 aresubjected to the magnetic saturation, so that the flux of the permanentmagnets 6 closing in the rotor 3 interlinks with the armature windings 2of the stator 1. Therefore, when the machine is not loaded, the inducedvoltage due to the interlinkage flux of the permanent magnets 6 is sosmall, whereby the flux of the permanent magnets 6 can be utilizedeffectively under the loaded condition. As to the other operation andeffect, this embodiment is similar to the 1st. embodiment.

[8th Embodiment]

FIG. 11 is a radial sectional view of a rotor of the reluctance typerotating machine of the 8th. embodiment of the present invention. Therotating machine of the embodiment is characterized in that, as to thegap between the rotor core 4 and the stator 1, a gap length about theinterpole 4 b in the radial direction is larger than that about the pole4 a. For example, the gap length 1 a of the pole 4 a is equal to 0.6 mm,while the gap length 1 b of the interpole 1 b is set to 1.8 mm. As otherconstituents are similar to those of the 1st. and 7th. embodiment, theiroverlapping descriptions are eliminated.

Since the gap length 1 a of the pole 4 a is smaller than the gap length1 b of the interpole 1 b, the magnetic unevenness is enlarged, so thatthe reluctance torque does increase. Simultaneously, since thecircumferential gap length of the interpole 4 b is relatively long,there is an increase in flux of each permanent magnet 6 closing in therotor 3 through the magnetic portion 9 as the magnetic path,accompanying a decrease in flux of the permanent magnet 6 interlinkingwith the stator windings 2.

When the flux of current overlaps at the time of the machine beingloaded, each magnetic portion 7 between the pole 4 a and the interpole 4b and the outer magnetic portion 9 are locally subjected to the magneticsaturation, so that the flux of the permanent magnets 6 closing in therotor 3 interlinks with the armature windings 2 of the stator 1.Therefore, when the machine is not loaded, the induced voltage due tothe interlinkage flux of the permanent magnets 6 is so small, wherebythe flux of the permanent magnets 6 can be utilized effectively underthe loaded condition. As to the other operation and effect, thisembodiment is similar to the 1st. and 7th. embodiments.

[9th Embodiment]

The rotating machine of this embodiment is identical to that of the 1st.embodiment of FIGS. 1 to 4 with respect to the basic constitution andtherefore, the overlapping descriptions are eliminated. According to theembodiment, there are established a radial thickness of each magneticportion 7, thickness and surface area of the permanent magnet 6, avolume of the non-magnetic portion 8, a thickness of the magneticportion between the non-magnetic portion 8 and the periphery of thecore, etc. on the ground that, when the machine is loaded, the flux ofarmature current in the direction of the central axis of the interpole 4b negates the flux of each permanent magnet 6 and therefore, theresultant composite flux in the interpole direction amounts tosubstantial zero.

When applying the load current, the flux φq of the armature currentnegates the flux φm of the permanent magnets 6, so that the compositeflux in the center axis of the interpole amounts to zero. Therefore, thevoltage induced by the flux in the central axis of the interpole becomesto be zero, too. Thus, since the terminal voltage is induced by the fluxin the direction of pole, low voltage and high output can be providedfor the rotating machine.

Additionally, the constant output characteristic can be obtained withease. As the reluctance torque is a product of both exciting current andtorque current component of the armature, the output is obtained by aproduct of the exciting current, the torque current component and therotating speed. Upon fixing the armature current component (torquecurrent) forming the flux in the direction of interpole axis into aconstant value so that the composite flux in the direction of centeraxis of the interpole amounts to zero, by adjusting the armature currentcomponent (exciting current) with respect to the rotating speed ininverse proportion to each other, the constant output characteristicwhere torque times rotating speed is constant can be accomplished. As tothe other operation and effect, this embodiment is similar to the 1st.embodiment.

[10th Embodiment]

The rotating machine of this embodiment is identical to that of the 1st.embodiment of FIGS. 1 to 4 with respect to the basic constitution andtherefore, the overlapping descriptions are eliminated. According to theembodiment, there are established a radial thickness of each magneticportion 7, thickness and surface area of the permanent magnet 6, avolume of the non-magnetic portion 8, a thickness of the magneticportion between the non-magnetic portion 8 and the periphery of thecore, etc. on the ground that, when the armature current componentforming the flux in the direction of center axis of the interpole ismaximum, the flux φq of armature current in the direction of the centralaxis of the interpole 4 b negates the flux 4 m of each permanent magnet6 and therefore, the resultant composite flux in the interpole directionamounts to substantial zero.

In the embodiment, the maximum current for the rotating machine isdivided into two vector components crossing at right angles, i.e., anarmature current component forming the flux in the direction of centeraxis of the interpole and another armature current forming the flux inthe direction of pole. When the maximum current of armature (compositevector) intersects the armature current component forming the flux inthe direction of center axis of interpole at angles of 45 degrees, amaximum of reluctance torque can be obtained. The rotating machine ofthe embodiment is constructed in a manner that, at this current phase,the flux of armature current in the direction of the central axis of theinterpole negates the flux of each permanent magnet 6 and therefore, theresultant composite flux in the interpole direction amounts tosubstantial zero. Therefore, when the induced voltage is raised duringthe machine's operation at a high rotating speed range, the machineallows the armature current component (i.e. exciting current component)forming the flux in the direction of pole to be adjusted smaller,whereby the constant induced voltage can be attained. Consequently, itis possible to realize a wide range of variable-speed operation and ahigh power factor under the constant output. As to the other operationand effect, this embodiment is similar to the 1st. embodiment.

[11th Embodiment]

The rotating machine of this embodiment is identical to that of the 1st.embodiment of FIGS. 1 to 4 with respect to the basic constitution andtherefore, the overlapping descriptions are eliminated. According to theembodiment, there are established a number of flux of the permanentmagnets 6 interlinking with the armature windings in case of zero inarmature current, a radial thickness of each magnetic portion 7,thickness and surface area of the permanent magnet 6, a volume of thenon-magnetic portion 8, a thickness of the magnetic portion between thenon-magnetic portion 8 and the periphery of the core, etc., so as tomeet the following conditions. That is, in connection with the armaturecurrent produced by the flux of the permanent magnets 6 when the machineis electrically closed in a short circuit, the above factors arerespectively determined in a manner that the heat derived fromJoule-loss originating in the above armature current is less than athermal allowable value of the machine or the braking force produced bythe above armature current is less than an allowable value of themachine.

Generally, if there is remained any flux of the permanent magnets 6which interlinks with the armature windings 2 when an electricalshort-circuit accident is caused in an inverter, a terminal or the like,the rotation of the rotor 3 causes an induced voltage to be generated.Due to this induced voltage, the short-circuit current may flow in thearmature windings for burning or an operation of the apparatus may belocked by excessive brake torque. As mentioned in the 1st. and 2nd.embodiments, since the high output of the machine is accomplished by theinterlinkage flux from small number of permanent magnets 6, it ispossible to reduce the induced voltage in order to establish bothshort-circuit current and brake less than the allowable values,respectively. Consequently, even if occurring the short-circuitaccident, it would be possible to prevent troubles in the rotatingmachine and the apparatus. As to the other operation and effect, thisembodiment is similar to the 1st. embodiment.

[12th Embodiment]

The reluctance type rotating machine of this embodiment is provided byarranging the permanent magnets 6 between the adjoining poles of therotor core 4 and fulfilling the cavities 8 as the first non-magneticparts with copper or aluminum material. The rotating machine of thisembodiment is identical to that of the 1st. and 4th. embodiments withrespect to other constituents and therefore, the overlappingdescriptions are eliminated.

With the arrangement of conductive materials of copper or aluminum inthe cavities 8, an eddy current is generated in the conductive materialswhen the rotor 3 does not synchronize with the rotating field, so thatthe rotor can enter its synchronous rotation. That is, the self-startingand stable rotation of the rotating machine can be realized. As to theother operation and effect, this embodiment is similar to the 1st. and4th. embodiments.

[13th Embodiment]

FIG. 12 is a radial sectional view of a rotor of the reluctance typerotating machine of the 13th. embodiment of the present invention.

According to the embodiment, many orifices are formed around theperiphery of the rotor core 4 and copper bars 13 are inserted into theorifices, respectively. The copper bars 13 have respective endselectrically connected with each other. The rotating machine of thisembodiment is identical to that of the 1st. and 4th. embodiments withrespect to other constituents and therefore, the overlappingdescriptions are eliminated.

Since the induced current flows in the copper bars 13 at the machine'sasynchronous operation, the self-starting and stable rotation of therotating machine can be realized. Further, it is possible to absorb theeddy current by harmonic current when driving the inverter. As to theother operation and effect, this embodiment is similar to the 1st. and4th. embodiments.,

[14th Embodiment]

FIGS. 13 and 14 are axially sectional views of a rotor of the reluctancetype rotating machine of the 14th. embodiment of the present invention.

The reluctance type rotating machine of the embodiment is characterizedby a pair of magnetic end rings 12 disposed on both axial ends of therotor core 4. The rotor 3 of the embodiment is constituted by the rotorcore 4 and the end rings 12. The other constitution is similar to thatof the rotating machine of the 1st. embodiment.

The rotating machine of the embodiment operates as follows.

When the rotor 3 is subjected to an armature reaction field in theopposite direction to the magnetized direction of each permanent magnet6 in the rotor core 4 by the armature current, a part of magnetic fluxφm of the permanent magnets 6 forms closed magnetic paths 51 eachflowing the core 4 in the axial direction, entering into the end ring 12and returning the core 4. That is, according to the embodiment, sincethe leakage flux can be produced effectively, it is possible to adjustthe amount of interlinkage flux between the armature windings 2 and thepermanent magnets 6, whereby the terminal voltage can be controlled bythe armature current with case. In addition, as shown in FIG. 14, it ispossible to adjust the ratio of leakage flux to effective flux bycontrolling a clearance 13 between the rotor core 4 and each end ring12. As to the other operation and effect, this embodiment is similar tothe 1st. embodiment.

[15th Embodiment]

FIG. 15A is a cross sectional view of the reluctance type rotatingmachine in accordance with the first embodiment of the presentinvention, taken along the radial direction of the rotor of the machine.As similar to the previously-mentioned embodiments, the machinecomprises the stator 1 provided with the armature windings 2 of fourpoles and the generally cylindrically-shaped rotor 3. As the structureof the rotor 3, the rotor core 4 is constituted by a generallycylindrical member of magnetic material, such as soft steel called“S45C”, or a laminated member of generally circular silicon steelplates. Formed at intervals of the width of a magnetic pole along thedirections of respective pole axes in the rotor core 4 are the cavities5 each of which is in the form of an semi-arrow. That is, according tothe embodiment, since four magnetic poles are cross-shaped in thearmature windings 2, the cavities 5 are formed so as to interposerespective poles therebetween from both sides of the pole,correspondingly.

In order to define the magnetic unevenness, respective fan-shapedportions each interposed by the adjoining poles of the core 4, namely,four interpoles have outer peripheries somewhat recessed in comparisonwith outer peripheries of the cross-shaped poles. Consequently, a gapportion 17 is defined between the periphery of each interpole and thestator 1. Note, as shown in FIG. 15A, each cavity 5 is formed to have anouter end positioned inside the periphery of each interpole in theradial direction of the rotor 3. Additionally, the cavities 5 are formedso that respective inner ends in the radial direction of the rotor 3 donot interfere with each other.

In the so-formed cavities 5, the rectangular permanent magnets 6, suchas magnets of Nd—Fe—B type, are embedded in a manner that respectivelongitudinal ends thereof come in touch with the inner ends of thecavities 5, while the other longitudinal ends of the magnets 6 leavetriangular spaces 5 a in the cavities 5. These permanent magnets 6 areretained in the cavities 5 by means of an adhesive, for example. Eachmagnet 6 is magnetized in a direction perpendicular to the pole axis.Additionally, the magnets 6 are arranged so that the flux φm generatedfrom the magnets 6 stands up to the leakage flux of the armaturewindings 2 flowing into the area of the interpoles. In detail, thepermanent magnets 6 on both sides of each pole as a center are bothidentical in magnetizing direction and perpendicular to the pole. Also,the permanent magnets 6 on both sides of each interpole as a center haveopposite magnetizing directions to each other in the circumferentialdirection of the rotor core 4.

FIG. 15B shows a modification of the reluctance type rotating machine ofFIG. 15A. In this rotating machine, fan-shaped cavities 8 are formed inthe interpole portion in the rotor core 4. The shape of the space 5 a ischanged to a rectangular shape so as not to interfere with the cavities8.

The above-mentioned reluctance type rotating machine operates asfollows.

FIG. 16 shows the flux distribution in the rotor 3 in a so-called“unloaded condition where no current flows in the armature windings 2 sothat the flux from the windings 2 does not flow in the rotor 3.Generally in the rotor structure where the permanent magnets 6 areembedded, the short-circuit current flows in the armature windings 2 inthe unloaded condition due to the magnetic flux φma generated from thepermanent magnets 6 themselves, so that the brake force is exerted onthe rotor 3. However, since the rotor 3 of the embodiment employs thestructure to leave a part of core outside each permanent magnet 6, theflux φma forms a closed circuit about each permanent magnet 6 as shownin FIG. 16, thereby nullifying the induced voltage generating in thearmature windings 2 in the unloaded condition. Therefore, no brakingforce is applied on the rotor 3, so that it is possible to maintain thesteady-state rotation of the rotor 3. Note, in order to prevent theinduced voltage from occurring in the armature windings 2, we, theinventor et al. found in accordance with our experiments it desirable toadjust the position of the embedded permanent magnets 6, in other words,a radial thickness of a core portion 7 at the circumferential end of theinterpole (i.e. a core portion between the space 5 a and a periphery ofthe interpole) so that at least the magnetic flux density of thepermanent magnets 6 interlinking with the armature windings 2 gets lessthan 0.1 [T] at the gap 17 under the “zero” current condition.

While, FIG. 17 shows the flux distribution in the rotor 3 under theloaded condition. In this state, since the current flows in the armaturewindings 2, the flux φd is generated by the armature current of d-axis.

The magnetic flux φd contains not only a main flux flowing in the polesof the rotor core 4 as the magnetic paths but a leakage flux passingfrom the pole to the adjoining pole through a core portion on theperiphery of the interpole. Due to the leakage flux and the flux φmafrom the permanent magnet 6, the core portion (magnetic part) 7 at thecircumferential margin of the interpole is saturate magnetically.Therefore, this magnetic saturation causes the flux φma from thepermanent magnet 6 to pass through the core portion 7 with difficulty,so that the flux φma is associated with that of the adjoining permanentmagnet 6, thereby forming the flux φmb passing through the interpolesfor the stator 1, as shown with broken lines of FIG. 17. Since the fluxφmb flows from the stator 1 to the interpoles of the rotor 3 and finallyinterlinks with the armature windings 2, both output and power factor ofthe machine can be improved.

FIG. 18 shows the magnetic flux φq in a direction along a center axis ofthe interpole, which originates in the armature current of q-axis. Theflux φq between the adjoining poles does define a magnetic path to passbetween the permanent magnets 6 on both sides of the interpole, run thevicinity of the rotor center and pass between the magnets 6 again.However, due to both actions of the flux φm from the permanent magnet 6toward the stator 1 and the increaseφmagnetic reluctance of the gap 17,the flux φq by the armature current of q-axis is reduced.

That is, because of the above-mentioned magnetizing direction of thepermanent magnets 6, the magnetic flux φm defines a magnetic path offirstly crossing each pole of the rotor 3, secondly entering from thecore portion of the interpole into the stator 1 through the gap 17 andfinally returning to the opposite magnet 6. Further, since the flux φmof the permanent magnet 6 is distributed in the opposite direction tothe flux φq, the former operates to repel the latter flux being about toenter into the interpole. Additionally, the “gap” flux density derivedfrom the armature current is reduced by the flux φq of the permanentmagnets 6 in the gap 17 about the interpole, so that a differencebetween the flux density in the gap 17 about the interpole and thatabout the pole is further increased. It means that the rotating machineof the embodiment has a large change in “gap” flux density with respectto the position of the rotor 3, thereby increasing the change inmagnetic energy. Consequently, the rotating machine is capable ofproducing a large output by this unevenness in gap flux density.

As mentioned above, since the rotating machine of the embodiment iscapable of reducing the interlinkage flux of the permanent magnets 6with the armature windings 2 when the machine is either unloaded orloaded lightly, it is possible to decrease the induced voltage, wherebythe core loss can be reduced. Accordingly, the high efficiency operationcan be accomplished when the machine is unloaded or loaded lightly.Furthermore, since the flux φm of each permanent magnet 6 closes in therotor core, it is also possible to prevent the magnet from beingdemagnetized. Owing to very few voltage induced by the magnets 6, therotating machine is capable of operating at a wide range of variablespeeds.

Further, even if an electrical short-circuit occurs the armaturewindings, an inverter, etc. during the rotor's rotation, theshort-circuit current does not flow since the induced voltage issubstantially equal to zero. Therefore, in spite of the short-circuit,it is possible to prevent an excessive braking force from being producedand the armature windings from being damaged.

Also in this embodiment, since the rectangular permanent magnets 6 areembedded in the axial direction of the rotor core 4 (of laminatedplates), it is possible to improve the strength of the rotor 3.

Although the cavities 5 are filled up with the permanent magnets 6 whileleaving the cavities 5 a in the above-mentioned embodiment, non-magneticmaterials 9 may be embedded in the remained cavities 5 a in themodification of the embodiment. Also in the modification, effectssimilar to those of the embodiment would be expected.

[16th Embodiment]

FIG. 20 is a cross sectional view of the reluctance type rotatingmachine in accordance with the 16th. embodiment of the presentinvention, taken along the radial direction of the rotor of the machine.As similar to the previously-mentioned embodiments, the machinecomprises the stator 1 provided with the armature windings 2 of fourpoles and the rotor 3 accommodated in the stator 1. The rotor 3 isprovided, at a center thereof, with a rotor shaft 30 for engagement withthe rotor core 4. The rotor core 4 is constituted by a generallycylindrical member of magnetic material, such as soft steel called“S45C”, or a laminated member of generally circular silicon steelplates. Formed at intervals of the width of a magnetic pole along thedirections of respective pole axes in the rotor core 4 are the cavities5 which have rectangular cross-sections. The rectangular permanentmagnets 6, such as magnets of Nd—Fe—B type, are securely embedded in thecavities 5 by an adhesive, for example. That is, according to theembodiment, since four magnetic poles 4 a are cross-shaped in rotor 3,while the permanent magnets 6 are arranged so as to interpose each pole4 a therebetween. Note, although the rotor shaft 30 is inserted into therotor core 4 in common with some later-mentioned embodiments includingthis embodiment, the rotor 3 may be provided by adhesively stackingcircular core plates each having no center opening for the shaft 30 inthe modification.

Each permanent magnet 6 is magnetized in a direction perpendicular tothe pole axis. Additionally, the permanent magnets 6 are arranged sothat the magnetic flux from the magnets 6 stands up to the leakage fluxof the armature windings 2 flowing into the area of the fan-shapedinterpoles 4 b. In detail, the permanent magnets 6 on both sides of onepole 4 a are identical to each other in magnetizing direction andrespectively magnetized in a direction perpendicular to the pole. Also,the permanent magnets 6 on both sides of each interpole 4 b haveopposite magnetizing directions to each other in the circumferentialdirection of the rotor core 4.

In the vicinity of the outer face of each pole 4 a interposed betweenthe opposing permanent magnets 6, a plurality (e.g. five) of bars 20having isosceles fan-shaped cross sections are embedded in the rotorcore 4 along the axial direction of the rotor 3 so as to direct theirpeaks to the outside. The deep groove bars 20 are made of conductivemagnetic material, such as aluminum-additive iron, silicon-additiveiron, etc. and adapted so as to conduct each other at both axial ends ofthe rotor 3, through the intermediary of not-shown conductive plates,for example. The sectional profile of each bar 20 may be rectangular.Alternatively, it may be oval.

The magnetic bars 20 operate as follows. At the start of the operationof the rotating machine, the induced current flows in the bars 20 by theflux of the armature windings 2, so that the starting torque is producedin the rotor 3, allowing the rotating machine to start by itself. Note,as similar to the core 4, since each magnetic bars 70 themselves areformed by the magnetic material, there is no influence on flux (mainflux) flowing the poles 4 a.

Additionally, according to the embodiment of the invention, a pair ofcircular-sectional cavities 21 are formed in the core portions on bothsides of a group of magnetic bars 18 embedded in each pole 4 a and alsopositioned outside the permanent magnets 6 in the radial direction ofthe rotor 3. Owing to the provision of the cavity 21, each boundarybetween the pole 4 a and the interpole 4 b is so clarified to interceptthe magnetic circuit, so that the magnetic reluctance is furtherincreased in each interpole 4 b. Accordingly, the change in magneticenergy is increased between the poles 4 a and the interpoles 4 b,thereby producing a great torque.

[17th Embodiment]

FIG. 21 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 17th. embodiment of the presentinvention.

According to this embodiment, both of the cavity 5 for each permanentmagnet 6 and outside cavity 8 in the 16th. embodiment may be replacedwith one rectangular cavity 9 where the permanent magnet 6 is arrangedso that a longitudinal end thereof abuts on the inner end of the cavity9.

The operation of the rotor 3 of the embodiment is similar to that of the16th. embodiment. That is, owing to a cavity portion remained in eachcavity 5, the boundary between the pole 4 a and the interpole 4 b isclarified to intercept the magnetic circuit. Note, since the cavity 5for magnet and the cavity 8 of the 16th. embodiment are replaced withonly one cavity in this embodiment, it is possible to reduce the numberof manufacturing processes in comparison with the 16th. embodiment,whereby the manufacturing cost can be saved.

[18th Embodiment]

FIG. 22 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 18th. embodiment of the presentinvention. According to the embodiment, a plurality of conductive bars23 having circular sections are embedded in the interpoles 4 b along theouter face of the rotor 3 although it looks like the rotor 3 of the16th. embodiment. Each conductive bar 10 is made of, for example,copper, aluminum, or the like, namely, non-magnetic material. Thus, atthe machine's starting, the induced current flows in the vicinity of theouter face of the interpoles 4 b, too. Therefore, the self-startcharacteristic of the machine can be improved. Further, because of theirnon-magnetism, the magnetic reluctance is further increased in theinterpoles 4 b in comparison with the 17th and 18th. embodiments, sothat the change in magnetic energy between the poles 4 a and theinterpoles 4 b is further increased to improve the output of therotating machine.

[19th Embodiment]

FIG. 23 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 19th. embodiment of the presentinvention. According to the embodiment, a plurality of non-magneticconductive bars 23 are embedded on the peripheries of the interpoles 4 bof the rotor 3 of FIG. 21. The operation of the rotating machine of theembodiment is similar to that of the 18th. embodiment.

[20th Embodiment]

FIG. 24 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 20th. embodiment of the presentinvention. According to the embodiment, a plurality of non-magneticconductive bars 24 having circular sections are inserted into thecavities 21 of FIG. 22. Consequently, each boundary between the pole 4 aand the interpole 4 b is clarified, so that the change in magneticenergy between the pole 4 a and the interpole 4 b is further increasedto improve the output of the machine.

[21st Embodiment]

FIG. 25 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 21st. embodiment of the presentinvention. This embodiment is similar to the embodiment of FIG. 20 butthe configuration of the rotor core 4 provided, in the interpoles 4 a,with four fan-shaped cavities 25. Consequently, by the action of highmagnetic reluctance of both permanent magnets 6 and cavities 25, theflux along the directions of interpole axes is reduced, so that thechange in magnetic energy between the pole 4 a and the interpole 4 b isfurther increased to improve the output of the machine.

[22nd Embodiment]

FIG. 26 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 22nd. embodiment of the presentinvention. This embodiment is similar to the embodiment of FIG. 21 butthe configuration of the rotor core 4 provided, in the interpoles 4 a,with four fan-shaped cavities 25, too. The operation of the machine ofthe embodiment is similar to that of the 21st. embodiment.

Note, as to the non-magnetic conductive bar 23 of FIGS. 22, 23 and 24,the configuration may be either rectangular or triangular in themodification of those embodiments.

[23-25th Embodiments]

FIGS. 27 to 29 are cross sectional views of the rotors 3 of thereluctance type rotating machine in accordance with the 23rd. to 25th.embodiments of the present invention, respectively. In common with thoseembodiments, the fan-shaped cavities 25 are formed in the rotors 4 ofFIGS. 22 to 24, respectively, as similar to the 21st. embodiment. Theoperation of the rotors 3 of those embodiments is identical to theoperation of the rotors 3 of the 18 to 20th. embodiments, except thatthe magnetic reluctance of the interpoles 4 b is increased by thecavities 25.

[26th Embodiment]

FIG. 30 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 26th. embodiment of the presentinvention. In this modification of the 25th. embodiment, the cavities 21of identical sections are arranged on the whole periphery of the rotor 3at regular intervals. In the cavities 21, some in the poles 4 a arefilled up with the magnetic conductive bars 27 extending in the axialdirection of the rotor 3, while the other cavities 21 in the interpoles4 b are filled up with the non-magnetic conductive bars 24 in the axialdirection of the rotor 3. Consequently, owing to the provision of theconductive bars 24, 27 of identical configurations on the periphery ofthe rotor 3, the induced current flows in the bars 24, 27 by the fluxfrom the armature windings 2 at the machine's starting, allowing themachine to start by itself.

[27th Embodiment]

FIG. 31 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 27th. embodiment, which issimilar to the 26th. embodiment. That is, according to the embodiment,the rotor 3 is provided with no magnetic conductive by abolishing thecavities 21 in the poles 4 a from the rotor 3 of the 26th. embodiment.Also in this rotor 3, a large induced current flows in the conductivebars 24 at the machine's start, so that the self-starting can beensured.

Meanwhile, in common with the 21 to 26th. embodiments where the cavities25 are formed in the interpoles 4 b, respective bridge portions (i.e.peripheral portions of the interpoles 4 b) of the rotor 3 has a tendencyto be deformed outward by its centrifugal force when the machine isrotating at high speed.

FIGS. 32 to 35 show respective cross sections of the rotor cores 4 eachprovided for the purpose of preventing the rotor 3 from being deformeddue to the machine's rotation at high speed. In the followingembodiments, each rotor core 4 of FIGS., 32 to 35 may be either disposedon both axial ends of an rotor core assembly or inserted into an axialintermediate position of the assembly, which may be obtained bylaminating a number of circular plates each shown in FIG. 30, forexample.

[28th Embodiment]

FIG. 32 shows a rotor core plate 4A as a constituent of the rotor inaccordance with the 28th. embodiment. In order to provide the rotor coreplate 4A, the fan-shaped cavities 25 are eliminated from the rotor core4 of FIG. 30, so that the rotor core plate 4A is completed with nocavity but the cavities 5 accommodating the permanent magnets 6.Consequently, in the rotor core 4 where the core plates 4A are arrangedon both axial ends of the rotor or one or more core plates 4A areinterposed in the rotor, it is possible to resist the centrifugal forcewhen the machine is rotating at high speed since the interpoles 4 b ofthe rotor are reinforced.

[29th Embodiment]

FIG. 33 shows a rotor core plate 4B as a constituent of the rotor inaccordance with the 29th. embodiment. According to the embodiment, thecore plate 4B is provided, in each interpole 4 b, with a cavity 28somewhat smaller than the cavity 25 of FIG. 30. Consequently, in therotor core 4 where the core plates 4B are arranged on both axial ends ofthe rotor or one or more core plates 4B are interposed in the rotor, theinterpoles 4 b of the rotor can be reinforced.

[30th Embodiment]

FIG. 34 shows a rotor core plate 4C as a constituent of the rotor inaccordance with the 30th. embodiment. Although this embodiment issimilar to the embodiment of FIG. 30 in terms of the arrangement ofconductive bars, the former embodiment differs from the latter in thatthe core plate 4C is provided, inside each interpole 4 b, with a bridgemember 29 extending outward in the radial direction of the rotor. Inassembly, one or more core plates 4C are interposed in the rotorobtained by laminating a number of rotor cores 4 of FIG. 30 in order toreinforce the interpoles 4 b of the rotor.

[31st Embodiment]

FIG. 35 shows a rotor core plate 4D as a constituent of the rotor inaccordance with the 31st. embodiment. Although this embodiment issimilar to the embodiment of FIG. 31 in terms of the rotor structure,the former embodiment differs from the latter in that the core plate 4Dis also provided, inside each interpole 4 b, with the bridge member 29extending outward in the radial direction of the rotor. In assembly, oneor more core plates 4D are interposed in the rotor obtained bylaminating a number of rotor cores 4 of FIG. 31 in order to reinforcethe interpoles 4 b of the rotor.

[32nd Embodiment]

FIG. 36 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 32nd. embodiment of theinvention. According to the embodiment, the rotor 3 has the cavities 25formed in the interpoles 4 b and is covered, on the whole periphery ofthe rotor 3, with a cylindrical member 30 of conductive material. Thematerial of the cylindrical member 30 may be non-magnetic material, forexample, copper, aluminum, or the like. Alternatively, the member 30 maybe made of magnetic material exhibiting fine conductivity.

As the result, when the machine operates to start, a starting torque isgenerated by the induced current flowing in the axial direction of themember 30, allowing the self-starting of the rotor 3. Note, since thisrotor 3 of the embodiment employing the cylindrical conductive member 30has a reduced number of components in comparison with that of theembodiment where a number of conductive bars are embedded in the rotorcore, the mechanical strength of the rotor can be improved whilefacilitating the production of the machine.

Note, as the material exhibiting fine conductivity, Cu—Fe alloy may beappropriate for the member 30. Additionally, when the thickness of thecylindrical member is established so as to be one to four times as largeas a rind thickness which would be determined by the permeability andelectrical conductivity, then it is possible to increase the startingtorque of the rotor and reduce a slip in synchronizing the machine,whereby the pull-in for the machine can be facilitated especially.

[33rd Embodiment]

FIG. 37 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 33rd. embodiment of theinvention. According to the embodiment, the rotor 3 is constituted by asubstantially cross-shaped core 31 extending along the pole-axes whileabolishing respective connecting portions (bridge parts) of theinterpoles, in a view of improving the yield of products when punching asteel plate into core plates. In the rotor core 31, each pole 31 a has aleading end formed in a dovetail-manner. While, a cylindrical member 32of conductive material is provided, on an inner face thereof, withdovetail grooves for engagement with the dovetail ends of the rotor core31. With the engagement, the so-constructed member 32 is fitted withrespect to the rotor core 31. In this way, the above-mentioned cavities25 of the rotor 3 are defined by the cross-shaped rotor core 31 and thecylindrical member 32 surrounding the core 31. The operation of themachine of the embodiment is similar to that of the 32nd. embodiment.Further, derived from the configuration of core, the yield of materialis improved, so that the manufacturing cost can be reduced. Since therotor core 31 is securely fixed with the cylindrical member 32 by theengagement of the dovetail ends with the dovetail grooves, there is nopossibility of slipping even if the rotor rotates at high speed, wherebythe strength of the rotor can be improved. Note, as to the magnetism ofthese conductive member 30, 32, it is preferable to make up them bynon-magnetic material in order to increase the magnetic reluctance ofthe interpoles 4 b and reduce the flux along the interpole-axes.Alternatively, the members 30, 32 may be made of magnetic materialexhibiting fine conductivity.

In case of employing the material of fine conductivity, as similar tothe 32nd. embodiment, when the thickness of the cylindrical member isestablished so as to be one to four times as large as the rind thicknesswhich would be determined by the permeability and electricalconductivity, then it is possible to increase the starting torque of therotor and reduce a slip in synchronizing the machine, whereby thepull-in for the machine can be facilitated especially.

[34th Embodiment]

FIG. 38 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 34th. embodiment of theinvention.

In the modification of the 33rd. embodiment, the conductor isconstituted by four curved shell members 33 succeeding to outer surfacesof the poles 4 a. Each shell member 33 is overlaid on the interpole 4 b,which is positioned inward of the leading end of the pole 4 a in theradial direction of the rotor 3, and is integrated with the interpole 4b by the engagement between the dovetail groove and a dovetailprojection 33 a of the member 33. According to the embodiment, since theinterpoles 4 b are covered with the shell members 33, the inducedcurrent flows in the interpoles 4 b at the machine's starting, allowingthe self-starting of the machine. Furthermore, since each shell member33 is adapted so as to succeed to the outer face of the pole 4 a inorder to form the rotor 3 of circular section, it is possible to reducethe air resistance (windage), whereby the rotational efficiency can beimproved.

[35th Embodiment]

FIG. 39 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 35th. embodiment of theinvention. According to the embodiment, a conductive shell member 34,which is similar to the shell member 33 of the 34th. embodiment, isfixed on the rotor core 4 in each cavity 25 of the rotor 3. Inoperation, the induced current flows in the shell members 34 positionedrelatively outside of the interpoles 4 b at the machine's starting,allowing the self-starting of the machine.

[36th Embodiment]

FIG. 40 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 36th. embodiment of theinvention, which is similar to the 33rd. and 34th. embodiments.According to the embodiment, the interpoles 4 b are abolished 9 from therotor 3 of FIG. 38, so that the rotor core 4 is formed to have agenerally cross-shaped section. Further, the circumferential ends ofeach pole 4 a are hook-shaped for engagement with circumferential endsof conductive shell members 35. Owing to this formation of the poles 4a, even if the centrifugal force of the rotor 3 is applied on themembers 35, they can be prevented from falling from the rotor 3. In thisway, each conductive shell member 35 of the embodiment constitutes apart of the rotor 3 at the interpole. In operation, the induced currentflows in the shell members 35 at the machine's starting, allowing theself-starting of the machine. Furthermore, since each shell member 33 isadapted so as to succeed the outer face of the pole 4 a, it is possibleto reduce the air resistance (windage), whereby the rotationalefficiency can be improved.

Although the shell members 35 are separated from each other in theembodiment, they may be replaced with a cylindrical member 37 of FIG. 41where the respective members 35 are connected with each other throughannular portions 36, in the modification.

[37th Embodiment]

FIG. 42 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 37th. embodiment of theinvention. The reluctance type rotating machine, as similar to the 1st.embodiment, includes the stator 1 having the four-pole armature windings2 and the rotor 3 accommodated in the stator 1.

This embodiment is characterized by a cylindrical conductive member 38covering the whole periphery of the rotor core 4. As shown in FIG. 43,the cylindrical conductive member 38 is provided, along thecircumferential direction, with a plurality of long slits 38 a eachextending in the axial direction of the member 38.

Due to the formation of the slits 38 a, the induced current at themachine's starting flows while defining a long path in the axial andcircumferential directions of the rotor, as shown with arrows A of FIG.43. Consequently, the magnetic coupling between the armature windingsand the rotor is reinforced to provide a great starting torque for therotor, allowing the self-starting of the rotor 3.

Note, the cylindrical member 38 of the embodiment is easy to bemanufactured and ensures its sufficient mechanical strength because ofits simple structure. Furthermore, since the periphery of the rotor 3 issmoothed by the member 38, it is possible to reduce the air resistance(windage), whereby the rotational efficiency can be improved.

As materials exhibiting fine conductivity, for example,aluminum-addition iron, silicon-addition iron, Cu—Fe alloy, or the likemay be adopted for material of the member 38. In this case, when thethickness of the cylindrical member 38 is established so as to be one tofour times as large as the rind thickness which would be determined bythe permeability and electrical conductivity, then it is possible toincrease the starting torque of the rotor and reduce a slip insynchronizing the machine, whereby the pull-in for the machine can befacilitated especially. Alternatively, if the member 38 is made ofmagnetic material as similar to that of the core 4, it would notinfluence on the flux (main flux) flowing the poles 4 a.

[38th Embodiment]

FIG. 44 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 38th. embodiment of theinvention. The reluctance type rotating machine of the embodimentdiffers from the 38th. embodiment in that the rotor 3 is provided, atthe interpoles, with the cavities 25. The other structure is similar tothat of the 38th. embodiment, including the cylindrical member 25.

According to the embodiment, since the flux along the interpole-axes isfurther reduced by the action of high magnetic reluctance due to thepermanent magnets 6 and the cavities 12, the change in magnetic energybetween the pole 4 a and the interpole 4 b is further increased therebyto improve the output of the machine.

[39th Embodiment]

FIG. 45 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 39th. embodiment of theinvention. The reluctance type rotating machine of the embodimentdiffers from the 39th. embodiment in terms of the configuration of therotor core 4. As similar to the embodiment of FIG. 37, the rotor 3 isconstituted by the substantially cross-shaped core 31 extending alongthe pole-axes while abolishing respective connecting portions (bridgeParts) of the interpoles, in a view of improving the yield of productsin punching a steel plate into core plates. Therefore, the leading endof each poles 31 a is shaped in the form of a dovetail, while thecylindrical member 38 is arranged outside the rotor core 4, providedwith dovetail grooves for engagement with the dovetail ends of the rotorcore 31.

As similar to the 37th. and 38th. embodiments, the cylindrical member 38is constituted by a conductive member having the plural slits 38 aarranged along the circumferential direction of the member, as shown inFIG. 43. The cavities 25 are defined by this cylindrical member 38 andthe cross-shaped core 31.

The operation of the cylindrical member 38 is quite identical to that ofthe member 38 of the 37th. and 38th. embodiments. Further, derived fromthe configuration of core, the yield of material is improved, so thatthe manufacturing cost can be reduced. Since the rotor core 31 issecurely fixed with the cylindrical member 32 by the engagement of thedovetail ends with the dovetail grooves, there is no possibility ofslipping even if the rotor rotates at high speed, whereby the strengthof the rotor can be improved.

Note, in case of employing the material of fine conductivity for thecylindrical member 38 and when the thickness of the cylindrical memberis established so as to be one to four times as large as the rindthickness which would be determined by the permeability and electricalconductivity, then it is possible to increase the starting torque of therotor and reduce a slip in synchronizing the machine, whereby thepull-in for the machine can be facilitated especially.

In common with the 37-39th. embodiments, however, the cylindrical member38 may be made of non-magnetic material to increase the magneticreluctance of the interpoles 4 b, in order to reduce the flux along theinterpole-axes.

[40th Embodiment]

FIG. 46A is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 40th. embodiment of theinvention. In a modification of the 39th. embodiment, the conductor ofthe rotor 3 is constituted by four curved shell members 39 each of whichis provided, along the circumferential direction, with a plurality ofslits 39 a of FIG. 46B. Each shell member 39 is overlaid on theinterpole 4 b, which is positioned inward of the leading end of the pole4 a in the radial direction of the rotor 3, and is integrated with theinterpole 4 b by the engagement between the dovetail groove and adovetail projection of the member 39. According to the embodiment, sincethe interpoles 4 b are covered with the shell members 39, the inducedcurrent flows in the interpoles 4 b at the machine's starting, allowingthe self-starting of the machine. Furthermore, since each shell member39 is adapted so as to succeed to the outer face of the pole 4 a inorder to form the rotor 3 of circular section, it is possible to reducethe air resistance (windage), whereby the rotational efficiency can beimproved.

Further, according to the embodiment, the shell members 39 areconstituted by non-magnetic material exhibiting the fine conductivity,for example, copper, aluminum, or the like. Therefore, when the machineis operated, the induced current also flows in the vicinity of the outerfaces of interpoles 4 b of the rotor 3 to improve the self-startingcharacteristic of the machine. Simultaneously, since the magneticreluctance is further increased in the interpoles 4 b due to theirnon-magnetism, the change in magnetic energy between the pole 4 a andthe interpole 4 b is further increased thereby to improve the output ofthe machine.

[41st Embodiment]

FIG. 47 is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 41st. embodiment of theinvention. According to the embodiment, the conductor of the rotor 3 isconstituted by four shell members 40 each of which is curved andprovided with the plural slits 39 a along the circumferential directionof the rotor 3 b. Each shell member 40 is fixed on the outside of eachcavity 25 of the rotor 3.

Accordingly, since the induced current of a long path flows in the shellmembers 40 positioned relatively outside of the interpoles 4 b at themachine's starting, the self-starting of the machine is facilitated.

[42nd Embodiment]

FIG. 48A is a cross sectional view of the rotor 3 of the reluctance typerotating machine in accordance with the 42nd. embodiment of theinvention, which is similar to the 40th. and 41st. embodiments.

According to the embodiment, the interpoles 4 b are abolished 9 from therotor 3 of FIG. 46A, so that the rotor core 4 is formed to have agenerally cross-shaped section. Further, the circumferential ends ofeach pole 4 a are hook-shaped for engagement with circumferential endsof conductive shell members 41. Owing to this formation of the poles 4a, even if the centrifugal force of the rotor 3 is applied on themembers 41, they can be prevented from being left out from the rotor 3.

Additionally, since the shell members 41 are connected with each otherthrough annular portions 41 b, 41 c at both axial ends of each member41, it is possible to form slits 41 a of long paths, which extend in theaxial direction of the rotor core 4 and are juxtaposed along thecircumferential direction of the rotor 3. Simultaneously, the shallmembers 41 are connected to the outer faces of the poles 4 a smoothly.

Consequently, the rotor core 4 of the embodiment can take effects issimilar to those of the embodiment of FIG. 45. Furthermore, since eachshell member 41 is adapted so as to succeed the outer face of the pole 4a, it is possible to reduce the air resistance (windage), whereby therotational efficiency can be improved. Further, when the machineoperates to start, the induced current of long path flows in the shellmembers 41, whereby the self-starting of the machine is facilitated.

Note, although the four shell members 41 are connected with each otherthrough the annular portions 41 b, 41 c thereby to constitute the singlecylindrical conductive member in this embodiment, the shell members 41may be separated from each other while eliminating the annular portions41 b, 41 c in a modification of the 42nd embodiment, as similar to the40th. and 41st. embodiments.

In common with the 37th.-42nd. embodiments, since the conductor outsidethe rotor core 4 has a plurality of slits formed in the cylindrical partof the rotor core and arranged along the circumferential direction ofthe rotor so as to each extend in the axial direction and therefore, theinduced current flows while forming long paths in the axial direction ofthe rotor at the machine's starting, the magnetic bonding between thearmature windings and the rotor is so reinforced to provide the startingtorque for the machine.

[43rd Embodiment]

FIG. 49 is a cross sectional view of the reluctance type rotatingmachine in accordance with the 43rd. embodiment of the presentinvention, taken along the radial direction of the rotor of the machine.As similar to the previously-mentioned embodiments, the machinecomprises the annular stator 1 provided with the armature windings 2 andthe rotor 3 accommodated in the stator 1.

According to the embodiment, the rotor 3 is constituted by a rotor core4 having a cross-shaped section and an annular member 42 abutting on therotor core 4. The rotor core 4 is constituted by a lamination ofnumerous steel plates obtained by punching (or wire-cutting) a steelplate of magnetic material (e.g. soft steel S45C, silicon steel) in across-shape, provided with the poles 4 a projecting outward in theradial direction of the rotor 3 and the interpoles 4 b (non-magneticspaces) each interposed between the adjoining poles 4 a in thecircumferential direction of the rotor 3. While, the annular member 42made of magnetic material identical to the rotor core 4 is constitutedas a cylindrical member having an annular section of a thickness T andalso extending in the axial direction of the rotor core 4 (i.e. adirection perpendicular to the drawing).

For integration with the rotor core 4, the annular member 42 is closelyfitted to the peripheries of the poles 4 a by means ofshrinkage-fitting, press-fitting, etc. Thus, there is caused no slipbetween the rotor core 4 and the annular member 42 during the operationof the rotor 3. Note, the radial thickness T of the annular member 42 isestablished smaller than a thickness t of a bridge portion 51 of anearlier rotor 50 of FIG. 54, (T<t). The reason of establishment is thatthe annular member 42 is formed into one body and therefore, the rotorcore 4 retained in such a member 42 can have the interpoles 4 b (andtheir vicinities) of which strength are respectively larger than thoseof the earlier rotor having bridge portions of the same thickness as themember 42. In other words, when it is required to ensure a certainstrength against each interpole of the rotor, the rotor 3 of theembodiment is capable of thinning the thickness T of the annular member43 in comparison with the thickness t of the earlier rotor (see FIG. 54)being provided for the same requirement.

The rotor 3 and the reluctance type rotating machine having the rotor 3operate as follows.

FIG. 50 shows the flux φd in the d-axis directions along the pole axesof the rotor core 4. As shown in the figure, since the flux φd flows inthe rotor core 4 of the poles 4 a as the magnetic path, the rotatingmachine has a structure where the flux is easy to flow because themagnetic reluctance of the magnetic path is remarkably small. While, asthe thickness T of the annular member 42 is smaller than the thickness tof the bridge portion 51 (FIG. 54), it is possible to reduce thequantity of leakage flux passing through the member 42 in comparisonwith that of leakage flux passing through the portion 51.

FIG. 51 shows the flux φq by the q-axis armature current along thedirections of radial axes passing the centers of the interpoles 4 b.Although the magnetic flux φq partially forms the magnetic pathscrossing the interpoles 4 b, the flux φq almost forms the magnetic pathspassing through the member 42 and sequentially flowing outward of theadjoining interpole 4 b in the radial direction of the rotor 3. Althoughthis flux distribution of the rotor 3 of the embodiment is similar tothat of the conventional rotor 50, the flux flowing the annular member42 is less than the flux flowing the bridge portions 51 of the rotor 50because of the establishment (T<t), accompanying the increase inmagnetic reluctance of the interpoles 4 b. Thus, as there is produced agreat magnetic unevenness with respect to the position of the rotor 3owing to the provision of the thinned annular member 42, the resultantmagnetic energy is remarkably changed to produce the large output of themachine.

Further, the rotor 3 of the embodiment is constituted by the unevenrotor core 4 covered with the annular member 42 as one body, it ispossible to make the thickness of the annular member 42 smaller thanthat of the earlier rotor upon the same requirement.

As to the material of the annular member 42, the use of material, ofwhich saturated flux density is lower than that of the material formingthe rotor core 4, would cause the flux of the q-axis direction to flowin the member 42 with difficulty in comparison with a case of employingthe same material as the rotor core 4 for the annular member 42. In sucha case, the leakage flux passing through the annular member 42 would bealso reduced in the flux of the d-axis direction thereby to increase thequantity of main flux, whereby the output of the machine could beimproved.

[44th Embodiment]

FIG. 52 is a cross sectional view of the rotor in accordance with the44th. embodiment of the present invention, taken along the radialdirection of the rotor. According to the embodiment, the rotor 3 ischaracterized in that, for example, the Nd—Fe—B type permanent magnets 6are disposed on both sides of each pole 4 a of the rotor core 4 in thecircumferential direction. Note, regarding the arrangement of theannular member 42, the embodiment is similar to the 43rd. embodiment.

The permanent magnets 6 are magnetized in the direction perpendicular tothe pole axis shown with an arrow A and also magnetized so as to repulsethe q-axis flux of the armature windings 2 entering into the interpoles4 b. In other words, the opposing magnets 6 interposing each pole 4 atherebetween are identical to each other in terms of the magnetizingdirection, perpendicular to the pole 4 a. While, the opposing magnets 6on both sides of each interpole 4 b are different from each other interms of the magnetizing direction, in the circumferential direction ofthe rotor 3 and also arranged in a manner that the flux from the magnets6 flows in the radial direction in the interpole 4 b. According to therotor 3 of the embodiment, since the flux of the permanent magnets 6operates to oppose the q-axis flux in addition to the operation of theannular member 52, the magnetic reluctance in the interpoles 4 b isfurther increased thereby to improve the output of the machine.

Meanwhile, the reluctance type rotating machine of the embodiment issuperior to the conventional reluctance type rotating machine in termsof the manufacturing process.

FIGS. 53A to 53D show an example of manufacturing the rotor of FIG. 52.Note, in this manufacturing process, the permanent magnets 6 aremagnetized by a magnetizer. That is, according to the manufacturingprocess, it is carried out to firstly laminate and fix numerous magneticplates, which have been cut in cross shapes, on each other, so that therotor core 4 having the poles 4 a and the interpoles 4 b is prepared(see FIG. 53A).

Next, the permanent magnets 6 before being magnetized are pasted on bothside faces of each pole 4 a by means of adhesives (see FIG. 53B).

Then, the rotor core 4 with the magnets 6 is set into a magnetizer 60 asshown in FIG. 54C and sequentially, the magnets 6 are magnetized inorder so as to have the above-mentioned magnetizing directions. Afterall the permanent magnets 6 have been magnetized, then the rotor core 4is detached from the magnetizer 60 and thereafter, the annular member 42is fitted to the rotor core 4 by means of shrinkage-fitting,press-fitting, or the like, thereby completing the rotor 3 (see FIG.53D).

In this way, since the rotor 3 includes the cross-shaped rotor core 4 asa constituent, it is possible to attach the pre-magnetized magnets 6 onthe poles 4 a with ease. Additionally, since the so-attached magnets 6expose on the rotor core 4, it is also possible to set the rotor core 4a having the magnets 6 in the magnetizer 60 easily.

In the modification of the above-mentioned method, thepreviously-magnetized magnets 6 may be attached on the side faces of thepoles 4 a of the rotor core 3 and thereafter, the annular member 42 maybe fitted on the rotor core 4. In such a case, owing to theconfiguration of the rotor core 4, it is possible to insert themagnetized magnets 6 into the core 4 with ease, thereby facilitating theassembling operation for completing the rotor 3.

Further, in the modification, the annular member 42 may be made ofnon-magnetic material in view of reducing the windage of the rotor 3simply.

Finally, it will be understood by those skilled in the art that theforegoing descriptions are preferred embodiments of the rotatingmachine, and that various changes and modifications may be made to thepresent invention without departing from the spirit and scope thereof.

What is claimed is:
 1. A reluctance type rotating machine comprising: astator having armature windings; a rotor having a rotor core, the rotorbeing provided, in a circumferential direction thereof, with alternatingmagnetic poles and interpoles in the rotor core; a plurality ofpermanent magnets arranged in the rotor core in the circumferentialdirection of the rotor, for negating armature flux passing betweenadjoining poles defined in the rotor; and a conductor arranged in aperipheral portion of the rotor core; wherein the conductor comprises aplurality of magnetic bars which are embedded in the vicinity of anouter face of each pole of the rotor core so as to extend in the axialdirection of the rotor and a plurality of non-magnetic bars which areembedded in the vicinity of an outer face of each interpole of the rotorcore so as to extend in the axial direction of the rotor.
 2. Areluctance type rotating machine as claimed in claim 1, wherein therotor has cavities formed in respective core portions outside thepermanent magnets in the radial direction of the rotor.
 3. A reluctancetype rotating machine as claimed in claim 2, wherein the rotor core isprovided, in the vicinity of an outer face of each interpole, with aplurality of non-magnetic conductor bars extending in the axialdirection of the rotor and generating an induced current therein.
 4. Areluctance type rotating machine as claimed in claim 3, comprising aplurality of non-magnetic conductor bars disposed in the cavities of therotor and extending in the axial direction of the rotor.
 5. A reluctancetype rotating machine as claimed in claim 1, wherein the conductor isadapted so as to cover an outer face of the rotor core.
 6. A reluctancetype rotating machine as claimed in claim 5, wherein the conductor has acylindrical shape so as to cover the whole outer face of the rotor core.7. A reluctance type rotating machine as claimed in claim 5, wherein theconductor comprises a plurality of shell members connected with theouter faces of the poles to cover the interpoles.
 8. A reluctance typerotating machine as claimed in claim 1, wherein the conductor isarranged in the vicinity of an outer face of each interpole of the rotorcore and curved along the circumferential direction of the rotor.
 9. Areluctance type rotating machine as claimed in claim 1, wherein theconductor has a plurality of slits arranged along the circumferentialdirection of the rotor and formed in a cylindrical portion of the rotorcore.
 10. A reluctance type rotating machine as claimed in claim 9,wherein the conductor is formed so as to cover the outer face of therotor core.
 11. A reluctance type rotating machine as claimed in claim10, wherein the conductor has a cylindrical shape so as to cover thewhole outer face of the rotor core.
 12. A reluctance type rotatingmachine as claimed in claim 11, wherein the conductor comprises aplurality of shell members which are connected with the outer faces ofthe poles to cover the interpoles.
 13. A reluctance type rotatingmachine as claimed in claim 9, wherein the conductor is arranged in thevicinity of an outer face of each interpole of the rotor core and curvedalong the circumferential direction of the rotor.
 14. A reluctance typerotating machine as claimed in claim 10, wherein the conductor is madeof conductive magnetic material.